Jeanne E Pemberton

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Courses

Scholarly Contributions

Chapters

• Hogan, D. E., Veres-Schalnat, T. A., Pemberton, J. E., & Maier, R. M. (2014). Biosurfactant Complexation of Metals and Applications for Remediation. In Research Trends and Applications. CRC Press.
• Hogan, D. E., Maier, R. M., Pemberton, J. E., & Veres-Schalnat, T. A. (2014). Biosurfactant Complexation of Metals and Applications for Remediation. In Biosurfactants: Research Trends and Applications(pp 278-310). Boca Raton: Taylor & Francis Group. doi:10.1201/b16383
• Pemberton, J. E. (2002). Raman Spectroelectrochemistry. In Handbook of Vibrational Spectroscopy (J.M. Chalmers, P.R. Griffiths, eds.)(pp 2711-2736). New York: John Wiley & Sons.
• Pemberton, J. E. (1998). Surface and Interface Analysis. In Encyclopedia of Chemical Technology(pp 541-582). New York: John Wiley & Sons.
• Pemberton, J. E. (1995). Raman Spectroscopy of Thin Organic Films. In Characterization of Thin Films (A. Ulman, ed.)(pp 87-112). Greenwich, CT: Manning Publications Co.
• Pemberton, J. E. (1995). Surface Raman Spectroscopy. In Handbook of Surface Imaging and Visualization (A.T. Hubbard, ed.)(pp 647-666). Boca Raton, FL: CRC Press.
• Pemberton, J. E. (1991). Surface Enhanced Raman Scattering. In In-Situ Studies of Electrochemical Interfaces: A Prospectus (H.D. Abruna, Ed.)(pp 193-265). Berlin: VCH Verlag Chemie.
• Coria-Garcia, J. C., & Pemberton, J. E. (1988). The Effect of UPD Pb on the SERS of Water at Ag Electrodes in Aqueous Chloride and Bromide Media. In Electrochemical Surface Science(pp 398-407). Washington, DC: American Chemical Society Sympoisum Series No. 378.
• Pemberton, J. E., & Guy, A. L. (1986). Raman Spectroscopy. In Metal Handbook: Materials Characterization(pp 126-138). Metals Park, OH: American Society for Metals.

Journals/Publications

• Pemberton, J. E., Blackburn, T. J., & Tyler, S. M. (2021). Optical Spectroscopy of Surfaces, Interfaces, and Thin Films. Analytical Chemistry, 94, 515-558.
• Pemberton, J. E., Palos Pacheco, R., & Kegel, L. L. (2021). Interfacial and Solution Aggregation Behavior of a Series of Bioinspired Rhamnolipid Congeners Rha-C14-Cx (x = 6, 8, 10, 12, 14). J. Phys. Chem. B, 125, 13585-13596.
• Compton, A. A., Deodhar, B. S., Fathi, A., & Pemberton, J. E. (2020). Optimization of a Chemical Synthesis for Rhamnolipids. ACS Sustainable Chem. Eng., 8, 8918-8927.
• Hogan, D. E., Tian, F., Malm, S. W., Kegel, L. L., Szabo, Z., Hunjan, A. S., Pemberton, J. E., Klimecki, W., Polt, R. L., & Maier, R. M. (2020). Biodegradability and Toxicity of Cellobiosides and Melibiosides. Journal of Surfactants and Detergents, 23, 715-724.
• Luft, C. M., Munusamy, E., Pemberton, J. E., & Schwartz, S. D. (2020). A Classical Molecular Dynamics Simulation Study of Interfacial and Bulk Solution Aggregation Properties of Dirhamnolipids. J. Phys. Chem. B, 124, 814-827. doi:10.1021/acs.jpcb.9b08800
• Pemberton, J. E., Sweedler, J. V., & Zhang, X. (2020). The Addition of Executive Editors: A Change for the Better!. Analytical Chemistry, 92, 6185-6186.
• Pemberton, J. E., Watts, K. E., Clary, K. E., & Lichtenberger, D. L. (2020). FTIR Spectroelectrochemistry of F4TCNQ Reduction Products and Their Protonated Forms. Anal. Chem., 7154-7161.
• Pemberton, J. E., Watts, K. E., Neelamraju, B., Moser, M., McCulloch, I., & Ratcliff, E. L. (2020). Thermally Induced Formation of HF4TCNQ- in F4TCNQ-doped Regioregular P3HT. J. Phys. Chem. Lett., 11, 6586-6592.
• Hogan, D. E., Tian, F., Malm, S. W., Olivares, C., Palos Pacheco, R., Simonich, M., Hunjan, A. S., Tanguay, R. L., Klimecki, W., Polt, R. L., Pemberton, J. E., Curry, J. E., & Maier, R. M. (2019). Biodegradability and toxicity of monorhamnolipid biosurfactant diastereomers. Journal of Hazardous Materials, 364, 600-607. doi:10.1016/j.jhazmat.2018.10.050
• Keener, J. E., Zambrano, D. E., Zhang, G., Zak, C. K., Reid, D. J., Deodhar, B. S., Pemberton, J. E., Prell, J., & Marty, M. T. (2019). Chemical Additives Enable Native Mass Spectrometry Measurement of Membrane Protein Oligomeric State within Intact Nanodiscs. J. Amer. Chem. Soc., 141, 1054-1061. doi:10.1021/jacs.8b11529
• Pemberton, J. E., & Sang, L. (2019). Chemistry at the Interface of -Sexithiophene and Vapor Deposited Ag, Al, Mg, and Ca: A Molecular View. J. Phys. Chem. C, 123, 18877-18888. doi:10.1021/acs.jpcc.9b06479
• Sang, L., & Pemberton, J. E. (2016). Unexpected Chemistry at the Interface of alpha-Sexithiophene and Vapor Deposited Ag, Al, Mg, and Ca. J. Am. Chem. Soc., submitted.
• Sang, L., & Pemberton, J. E. (2019). Penetration and Reaction Depths of Vapor Deposited Ag, Mg, Al and Ca on Oligothiophene Thin Films. Chem. Mater., 31, 6908-6917. doi:10.1021/acs.chemmater.9b01313
• Wang, H., & Pemberton, J. E. (2019). Direct Nanoscopic Measurement of Laminar Slip Flow Penetration of Deformable Polymer Brush Surfaces: Synergistic Effect of Grafting Density and Solvent Quality. Langmuir, 35, 13646-13655. doi:10.1021/acs.langmuir.9b02357
• Watts, K. E., Blackburn, T. J., & Pemberton, J. E. (2019). Optical Spectroscopy of Surfaces, Interfaces, and Thin Films: A Status Report. Anal. Chem., 91, 4235-4265. doi:10.1021/acs.analchem.9b00735
• Watts, K. E., Neelamraju, B., Ratcliff, E. L., & Pemberton, J. E. (2019). Stability of Charge Transfer States in F4TCNQ-doped P3HT. Chem. Mater., 31, 6986-6994. doi:10.1021/acs.chemmater.9b01549
• Watts, K. E., Nguyen, T., Tremolet de Villers, B. J., Neelamraju, B., Anderson, M. A., Braunecker, W. A., Ferguson, A. J., Larsen, R. E., Larson, B. W., Owczarczyk, Z. R., Pfeilsticker, J. R., Pemberton, J. E., & Ratcliff, E. L. (2019). Stability of push-pull small molecule donors for organic photovoltaics: spectroscopic degradation of acceptor endcaps on benzo[1,2-b: 4,5-b’]dithiophene cores. J. Mater. Chem. A, 7, 19984-19995. doi:10.1039/c9ta06310b
• Luft, C. M., Munusamy, E., Pemberton, J. E., & Schwartz, S. D. (2018). Molecular Dynamics Simulation of the Oil Sequestration Properties of a Nonionic Rhamnolipid. J. Phys. Chem. B, 122, 3944-3952. doi:10.1021/acs.jpcb.7b11959
• Munusamy, E., Pemberton, J. E., Luft, C. M., & Schwartz, S. D. (2018). Unraveling the Differential Aggregation of Anionic and Nonionic Monorhamnolipids at the Interfaces: A Classical Molecular Dynamics Simulation Study. J. Phys. Chem. B, 122, 6403-6416. doi:10.1021/acs.jpcb.8b03037
• Neelamraju, B., Watts, K. E., Pemberton, J. E., & Ratcliff, E. L. (2018). Correlation of Coexistent Charge Transfer States in F4TCNQ-Doped P3HT with Microstructure. J. Phys. Chem. Lett., 9, 6871-6877. doi:10.1021/acs.jpclett.8b03104
• Eisman, R. J., Munusamy, E., Kegel, L. M., Hogan, D. E., Maier, R. M., Schwartz, S. D., & Pemberton, J. E. (2017). Evolution of aggregate structure in solutions of anionic monorhamnolipids: experimental and computational results. Langmuir, 33, 7412-7424.
• Munusamy, E., Luft, C. M., Pemberton, J. E., & Schwartz, S. D. (2017). Structural Properties of Nonionic Monorhamnolipid Aggregates in Water Studied by Classical Molecular Dynamics Simulations. Journal of Physical Chemistry B, 121, 5781-5793. doi:10.1021/acs.jpcb.7b00997
• Palos Pacheco, R., Eismin, R. J., Coss, C. S., Wang, H., Maier, R. M., Polt, R. L., & Pemberton, J. E. (2017). Synthesis and Characterization of Four Diastereomers of Monorhamnolipids. Journal of the American Chemical Society, 139, 5125-5132.
• Pemberton, J. E., Hogan, D. E., & Maier, R. M. (2017). Rhamnolipid Biosurfactants Preferentially Complex Rare Earth Elements. Journal of Hazardous Materials, 340, 171-178.
• Wang, H., & Pemberton, J. E. (2017). Effect of Solvent Quality on Laminar Slip Flow Penetration of Poly(N-isopropylacrylamide) Films with an Exploration of Mass Transport Mechanism. Langmuir, 33, 7468-7478.
• Kegel, L. L., Szabo, L. Z., Polt, R. L., & Pemberton, J. E. (2016). Alkyl-melibioside and Alkyl-cellobioside Solution Phase Properties: Effect of Sugar Headgroup and Alkyl Chain Length on Surfactant Performance. Green Chemistry, 18, 4446-4460. doi:DOI: 10.1039/C6GC00436A
• Paniagua, S. A., Giordano, A. J., Smith, O. L., Barlow, S., Li, H., Armstrong, N. R., Pemberton, J. E., Bredas, J., Ginger, D. S., & Marder, S. R. (2016). Phosphonic Acids for Interfacial Engineering of Transparent Conductive Oxides. Chemical Reviews, 116, 7117-7158.
• Sang, L., Knesting, K. M., Bulusu, A., Sigdel, A. K., Giordano, A. J., Marder, S. R., Berry, J. J., Graham, S., Ginger, D. S., & Pemberton, J. E. (2016). Effect of Time and Deposition Method on Quality of Phosphonic Acid Modifier Self-assembled Monolayers on Indium Zinc Oxide. Appl. Surf. Sci., 389, 190-198.
• Szabo, L., Hanrahan, D. J., Jones, E. M., Martin, E., Pemberton, J. E., & Polt, R. L. (2016). Preparation of S-Glycoside Surfactants and Cysteine Thioglycosides. Carbohydrate Research, 422, 1-4.
• Boxley, C. J., Pemberton, J. E., & Maier, R. M. (2015). Rhamnolipids and related biosurfactants for cosmetics and cosmeceutical markets. INFORM (International News on Fats, Oils, and related Materials), 26, 206-210.
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• Matz, D. L., Soujoudi, H., Graham, S., & Pemberton, J. E. (2015). Signature Vibrational Bands for Defects in CVD Single Layer Graphene by Surface Enhanced Raman Spectroscopy. Journal of Physical Chemistry Letters, 6, 964-969.
• Pemberton, J. E., Sang, L., & Matz, D. L. (2015). Understanding the Reaction Chemistry of 2,2′:5′,2′′-Terthiophene Films with Vapor Deposited Ag, Al and Ca. Journal of Physical Chemistry C, 119, 24290-24298.
• Pemberton, J. E., Sweedler, J. V., Armstrong, D. W., Bab, Y., Desmet, G., Dovichi, N., Ewing, A. E., Fenslau, C. C., Kennedy, R. T., Larive, C. S., Ligler, F. S., McCreery, R. L., Niessner, R., Tan, W., Walt, D. R., Yatess III, J. R., Zenobi, R., & Zhang, X. (2015). The Scope of Analytical Chemistry. Analytical Chemistry, 87, 6425.
• Pemberton, J. E., Wang, H., Cheng, L., & Saez, A. E. (2015). Flow Field Penetration in Thin Nanoporous Polymer Films under Laminar Flow by Förster Resonance Energy Transfer Coupled with Total Internal Reflectance Fluorescence Microscopy. Analytical Chemistry, 87, 11746-11754.
• Sang, L., Mudalige, A., Sigdel, A. K., Giordano, A. J., Marder, S. R., Berry, J. J., & Pemberton, J. E. (2015). PM-IRRAS Determination of Molecular Orientation of Phosphonic Acid Self-Assembled Monolayers on Indium Zinc Oxide. Langmuir, 31, 5603-5613.
• Khosroabadi, A. A., Matz, D. L., Gangopadhyay, P., Pemberton, J. E., & Norwood, R. A. (2014). Study of the C60/Ag Interface of a Large Area Nanoarchitectured Ag Substrate using Surface Enhanced Raman Scattering. Journal of Physical Chemistry C, 118, 18027-18034.
• Pemberton, J. E., & Soemo, A. R. (2014). Combined Quenching Mechanism of Anthracene Fluorescence by Cetylpyridinium Chloride in Sodium Dodecyl Sulfate Micelles. Journal of Fluorescence, 24, 295-299.
• Pemberton, J. E., Mudalige, A., & Yoo, H. (2014). Thickness, Composition, and Molecular Structure of Residual Thin Films Formed by Forced Dewetting of Ag from Glycerol/D2O Solutions. Langmuir, 30, 15181-15192.
• Zhang, L., Pemberton, J. E., & Maier, R. M. (2014). Effect of fatty acid substrate chain length on Pseudomonas aeruginosa ATCC 9027 monorhamnolipid yield and congener distribution. Process Biochemistry.
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  Abstract: Rhamnolipids are surface-active molecules produced by Pseudomonas aeruginosa as congener mixtures. They are considered "green" alternatives to synthetic surfactants used in industrial, remediation and pharmaceutical applications. Optimizing yield as well as controlling congener distribution are necessary steps for successful commercialization of rhamnolipids. This study used a mixture of glucose and fatty acids of different chain length (C12-C22) and saturation (C18:1 and C18:2) to produce monorhamnolipids and determine the effect of fatty acid substrates on rhamnolipid yield, percent carbon conversion and congener distribution. Results show that 1% glucose + 0.25% stearic acid (C18) produced the greatest yield (2.1 g L-1) compared to other glucose-fatty acid combinations (0.8-1.8 g L-1). Various glucose + C18 ratios were then tested to optimize yield and percent substrate carbon conversion to monorhamnolipid. Results revealed a positive linear correlation between the mass percent of C18 used and the percent carbon conversion. A mass percent of 67% C18 was optimal resulting in a 44% carbon conversion and a yield of 13.7 g L-1 monorhamnolipid. For all fatty acid substrates tested, the RhaC10C10 was the most abundant and RhaC10C12:1 was the least abundant of the four major congeners produced. However, the relative amount of RhaC10C8 and RhaC10C12 congeners was dependent on several factors: in general, fatty acid substrates with relatively short chain length (C12 and C14), unsaturated fatty acid substrate (C18:2), and longer cultivation time resulted in a higher RhaC10C8/RhaC10C12 ratio. These findings will assist in mass production of monorhamnolipids and controlling the specific congeners produced. © 2014 Elsevier Ltd. All rights reserved.
• Cocilovo, B., Amooali, A., Lopez-Santiago, A., Favela, J., Islam, S., Duong, B., Gangopadhyay, P., Fallahi, M., Pemberton, J. E., Thomas, J., & Norwood, R. A. (2013). Effect of modular diffraction gratings on absorption in P3HT:PCBM layers. Applied Optics, 52(5), 1025-1034.
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  PMID: 23400064;Abstract: Various gratings with 700 nm feature spacings are patterned on the reverse side of organic solar cell active layers to increase the path length and constrain light to the cell through total internal reflection. The absorption enhancementis studied for 15, 40, and 120 nm active layers. We were able to confine 9% of the incident light over the wavelength range of 400-650 nm, with thinner gratings having a greater enhancement potential. The measurement setup utilizing an integrating sphere to fully characterize scattered or diffracted light is also fully described. © 2013 Optical Society of America.
• Gliboff, M., Sang, L., Knesting, K. M., Schalnat, M. C., Mudalige, A., Ratcliff, E. L., Hong, L. i., Sigdel, A. K., Giordano, A. J., Berry, J. J., Nordlund, D., Seidler, G. T., Brédas, J., Marder, S. R., Pemberton, J. E., & Ginger, D. S. (2013). Erratum: Orientation of phenylphosphonic acid self-assembled monolayers on a transparent conductive oxide: A combined NEXAFS, PM-IRRAS, and DFT study (Langmuir (2013) 29:7 (2166-2174) DOI: 10.1021/la304594t). Langmuir, 29(12), 4176-.
• Gliboff, M., Sang, L., Knesting, K. M., Schalnat, M. C., Mudalige, A., Ratcliff, E. L., Hong, L. i., Sigdel, A. K., Giordano, A. J., Berry, J. J., Nordlund, D., Seidler, G. T., Brédas, J., Marder, S. R., Pemberton, J. E., & Ginger, D. S. (2013). Orientation of phenylphosphonic acid self-assembled monolayers on a transparent conductive oxide: A combined NEXAFS, PM-IRRAS, and DFT study. Langmuir, 29(7), 2166-2174.
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  PMID: 23379837;Abstract: Self-assembled monolayers (SAMs) of dipolar phosphonic acids can tailor the interface between organic semiconductors and transparent conductive oxides. When used in optoelectronic devices such as organic light emitting diodes and solar cells, these SAMs can increase current density and photovoltaic performance. The molecular ordering and conformation adopted by the SAMs determine properties such as work function and wettability at these critical interfaces. We combine angle-dependent near-edge X-ray absorption fine structure (NEXAFS) spectroscopy and polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) to determine the molecular orientations of a model phenylphosphonic acid on indium zinc oxide, and correlate the resulting values with density functional theory (DFT). We find that the SAMs are surprisingly well-oriented, with the phenyl ring adopting a well-defined tilt angle of 12-16 from the surface normal. We find quantitative agreement between the two experimental techniques and density functional theory calculations. These results not only provide a detailed picture of the molecular structure of a technologically important class of SAMs, but also resolve a long-standing ambiguity regarding the vibrational-mode assignments for phosphonic acids on oxide surfaces, thus improving the utility of PM-IRRAS for future studies. © 2013 American Chemical Society.
• Matz, D. L., Ratcliff, E. L., Meyer, J., Kahn, A., & Pemberton, J. E. (2013). Deciphering the metal-C₆₀ interface in optoelectronic devices: Evidence for C₆₀ reduction by vapor deposited Al. ACS Applied Materials and Interfaces, 5(13), 6001-6008.
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  PMID: 23734813;Abstract: The formation of interfacial midgap states due to the reduction of buckminsterfullerene (C60) to amorphous carbon upon subsequent vapor deposition of Al is confirmed using Raman spectroscopy and X-ray, ultraviolet, and inverse photoemission spectroscopies. We demonstrate that vapor deposition of Al results in n-type doping of C60 due to an electron transfer from Al to the LUMO of C60, resulting in the formation of midgap states near the C60 Fermi level. Raman spectroscopy in ultrahigh vacuum clearly identifies the presence of the C60 anion radical (C60•-) as well as amorphous carbon created by further degradation of C60•-. In contrast, the interface formed by vapor deposition of Ag shows only a slight Ag/C60 interfacial charge displacement with no evidence for complete metal-to-C 60 electron transfer to form the anion radical or its further degradation products. These results confirm previous speculations of metal-induced chemical damage of C60 films after Al deposition, which is widely suspected of decreasing charge collection efficiency in OPVs, and provide key insight into charge collection at metal/organic interfaces in such devices. © 2013 American Chemical Society.
• Pemberton, J., Matz, D. L., Ratcliff, E. L., Meyer, J., Kahn, A., & Pemberton, J. E. (2013). Deciphering the metal-C60 interface in optoelectronic devices: evidence for C60 reduction by vapor deposited Al. ACS applied materials & interfaces, 5(13).
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  The formation of interfacial midgap states due to the reduction of buckminsterfullerene (C60) to amorphous carbon upon subsequent vapor deposition of Al is confirmed using Raman spectroscopy and X-ray, ultraviolet, and inverse photoemission spectroscopies. We demonstrate that vapor deposition of Al results in n-type doping of C60 due to an electron transfer from Al to the LUMO of C60, resulting in the formation of midgap states near the C60 Fermi level. Raman spectroscopy in ultrahigh vacuum clearly identifies the presence of the C60 anion radical (C60(•-)) as well as amorphous carbon created by further degradation of C60(•-). In contrast, the interface formed by vapor deposition of Ag shows only a slight Ag/C60 interfacial charge displacement with no evidence for complete metal-to-C60 electron transfer to form the anion radical or its further degradation products. These results confirm previous speculations of metal-induced chemical damage of C60 films after Al deposition, which is widely suspected of decreasing charge collection efficiency in OPVs, and provide key insight into charge collection at metal/organic interfaces in such devices.
• Pemberton, J., Wang, H., Coss, C. S., Mudalige, A., Polt, R. L., & Pemberton, J. E. (2013). A PM-IRRAS investigation of monorhamnolipid orientation at the air-water interface. Langmuir : the ACS journal of surfaces and colloids, 29(14).
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  The rhamnolipid biosurfactants have been considered as possible "green" alternatives to synthetic surfactants due to their greater compatibility with the environment and excellent surface active properties. In order to understand the molecular orientation of rhamnolipids at the air-water interface, a new monorhamnolipid with two octadecyl chains, Rha-C18-C18, has been studied at the air-water interface with polarization modulated-infrared reflection absorption spectroscopy (PM-IRRAS). Since rhamnolipids possess a carboxylic acid, and hence exhibit pH-dependent properties, their water surface orientation is studied in solutions of pH 2, 5, and 8. Rhamnolipids have also been reported to form strong complexes with Pb(2+); thus, the effect of the presence of Pb(2+) on molecular orientation at the interface is also investigated. PM-IRRA spectra indicate an increase in alkyl chain order and a decrease in alkyl chain tilt angle as the surface pressure of the monolayer increases, with pH-independent tilt angles ranging from 63° to 45°. Molecular modeling using Spartan provides insight into the cause of this large tilt angle as being due to the nature of the monorhamnolipid packing at the air-water interface as dictated by its large hydrophilic headgroup.
• Polt, R. L., Coss, C. S., Wang, H., Mudalige, A., & Pemberton, J. E. (2013). A PM-IRRAS Investigation of Monorhamnolipid Orientation at the Air-Water Interface. Langmuir, 29(14), 4441-4450.
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  The rhamnolipid biosurfactants have been considered as possible "green" alternatives to synthetic surfactants due to their greater compatibility with the environment and excellent surface active properties. In order to understand the molecular orientation of rhamnolipids at the air-water interface, a new monorhamnolipid with two octadecyl chains, Rha-C18-C18, has been studied at the air-water interface with polarization modulated-infrared reflection absorption spectroscopy (PM-IRRAS). Since rhamnolipids possess a carboxylic acid, and hence exhibit pH-dependent properties, their water surface orientation is studied in solutions of pH 2, 5, and 8. Rhamnolipids have also been reported to form strong complexes with Pb2+; thus, the effect of the presence of Pb2+ on molecular orientation at the interface is also investigated. PM-IRRA spectra indicate an increase in alkyl chain order and a decrease in alkyl chain tilt angle as the surface pressure of the monolayer increases, with pH-independent tilt angles ranging from 63 degrees to 45 degrees. Molecular modeling using Spartan provides insight into the cause of this large tilt angle as being due to the nature of the monorhamnolipid packing at the air-water interface as dictated by its large hydrophilic headgroup.
• Wang, H., Coss, C. S., Mudalige, A., Polt, R. L., & Pemberton, J. E. (2013). A PM-IRRAS investigation of monorhamnolipid orientation at the air-water interface. Langmuir, 29(14), 4441-4450.
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  PMID: 23406083;Abstract: The rhamnolipid biosurfactants have been considered as possible "green" alternatives to synthetic surfactants due to their greater compatibility with the environment and excellent surface active properties. In order to understand the molecular orientation of rhamnolipids at the air-water interface, a new monorhamnolipid with two octadecyl chains, Rha-C18-C18, has been studied at the air-water interface with polarization modulated-infrared reflection absorption spectroscopy (PM-IRRAS). Since rhamnolipids possess a carboxylic acid, and hence exhibit pH-dependent properties, their water surface orientation is studied in solutions of pH 2, 5, and 8. Rhamnolipids have also been reported to form strong complexes with Pb2+; thus, the effect of the presence of Pb2+ on molecular orientation at the interface is also investigated. PM-IRRA spectra indicate an increase in alkyl chain order and a decrease in alkyl chain tilt angle as the surface pressure of the monolayer increases, with pH-independent tilt angles ranging from 63 to 45. Molecular modeling using Spartan provides insight into the cause of this large tilt angle as being due to the nature of the monorhamnolipid packing at the air-water interface as dictated by its large hydrophilic headgroup. © 2013 American Chemical Society.
• Coss, C., Carrocci, T., Maier, R. M., Pemberton, J. E., & Polt, R. (2012). Minimally competent lewis acid catalysts: Indium(III) and bismuth(III) salts produce rhamnosides (=6-deoxymannosides) in high yield and purity. Helvetica Chimica Acta, 95(12), 2652-2659.
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  Abstract: Glycosylation of decan-1-ol (2), (±)-decan-2-ol (3), and (±)-methyl 3-hydroxydecanoate (4) with L-rhamnose peracetate 5 to produce rhamnosides (=6-deoxymannosides) 6, 7, and 8 in the presence of Lewis acids BF3×Et2O, Sc(OTf)3, InBr3, and Bi(OTf)3 was studied (Table1). While the strong Lewis acids BF 3×Et2O and Sc(OTf)3 were effective as glycosylation promoters, they had to be used in excess; however, glycosylation required careful control of reaction times and temperatures, and these Lewis acids produced impurities in addition to the desired glycosides. Enantiomerically pure rhamnosides (R)-1 and (S)-1 (Fig.) were obtained from L-rhamnose peracetate 5 and (±)-benzyl 3-hydroxydecanoate (9) via the diastereoisomeric rhamnosides 10 (Table2; Scheme3). The much weaker Lewis acids InBr3 and Bi(OTfl)3 produced purer products in high yield under a wider range of conditions (higher temperatures), and were effective glycosylation promoters even when used catalytically (
• Matz, D. L., & Pemberton, J. E. (2012). Reaction chemistry of solid-state pyridine thin films with Vapor deposited Ag, Mg, and Al. Journal of Physical Chemistry C, 116(21), 11548-11555.
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  Abstract: The reaction of pyridine in thin solid-state films with post-deposited Ag, Mg, and Al is investigated using surface Raman spectroscopy in ultrahigh vacuum. Vapor-deposited Ag forms metallic nanoparticles on the pyridine film, resulting in surface enhancement of the Raman scattering (SERS), with no reaction chemistry evident. Mg and Al react with pyridine by electron transfer to form radical anion intermediates, some of which are stabilized by entrapment in the solid pyridine matrix. With Mg, slight SERS enhancement is observed along with Mg-to-pyridine electron transfer to form pyridyl radical anions, some of which dimerize to 4,4′-bipyridine with loss of MgH 2 and a neutral Mg atom. With Al, the reaction chemistry is initiated by a similar Al-to-pyridine electron transfer, but the radical anions so formed undergo further degradation to amorphous carbon. In total, these results demonstrate the complex reaction chemistry that can occur between heterocycles in the solid state and low work function metal atoms. © 2012 American Chemical Society.
• Matz, D. L., Schalnat, M. C., & Pemberton, J. E. (2012). Reaction of thin films of solid-state benzene and pyridine with calcium. Journal of the American Chemical Society, 134(31), 12989-12997.
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  Abstract: The reaction between small organic molecules and low work function metals is of interest in organometallic, astronomical, and optoelectronic device chemistry. Here, thin, solid-state, amorphous benzene and pyridine films are reacted with Ca at 30 K under ultrahigh vacuum with the reaction progress monitored by Raman spectroscopy. Although both films react with Ca to produce product species identifiable by their vibrational spectroscopic signatures, benzene is less reactive with Ca than pyridine. Benzene reacts by electron transfer from Ca to benzene producing multiple species including the phenyl radical anion, the phenyl radical, and the benzyne diradical. Pyridine initially reacts along a similar electron transfer pathway as indicated by the presence of the corresponding pyridyl radical and pyridyne diradical species, but these pyridyl radicals are less stable and subject to further ring-opening reactions that lead to a complex array of smaller molecule reaction products and ultimately amorphous carbon. The elucidation of this reaction pathway provides insight into the reactions of aromatics with Ca that are relevant in the areas of catalysis, astrochemistry, and organic optoelectronics. © 2012 American Chemical Society.
• Pemberton, J. E. (2012). Analytical chemistry is alive and well all over Africa!. Analytical Chemistry, 84(19), 8095-.
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  PMID: 23025521;
• Pemberton, J., Matz, D. L., Schalnat, M. C., & Pemberton, J. E. (2012). Reaction of Thin Films of Solid-State Benzene and Pyridine with Calcium. Journal of the American Chemical Society.
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  The reaction between small organic molecules and low work function metals is of interest in organometallic, astronomical, and optoelectronic device chemistry. Here, thin, solid-state, amorphous benzene and pyridine films are reacted with Ca at 30 K under ultrahigh vacuum with the reaction progress monitored by Raman spectroscopy. Although both films react with Ca to produce product species identifiable by their vibrational spectroscopic signatures, benzene is less reactive with Ca than pyridine. Benzene reacts by electron transfer from Ca to benzene producing multiple species including the phenyl radical anion, the phenyl radical, and the benzyne diradical. Pyridine initially reacts along a similar electron transfer pathway as indicated by the presence of the corresponding pyridyl radical and pyridyne diradical species, but these pyridyl radicals are less stable and subject to further ring-opening reactions that lead to a complex array of smaller molecule reaction products and ultimately amorphous carbon. The elucidation of this reaction pathway provides insight into the reactions of aromatics with Ca that are relevant in the areas of catalysis, astrochemistry, and organic optoelectronics.
• Zhang, L., Veres-Schalnat, T. A., Somogyi, A., Pemberton, J. E., & Maiera, R. M. (2012). Fatty acid cosubstrates provide β-oxidation precursors for rhamnolipid biosynthesis in pseudomonas aeruginosa, as evidenced by isotope tracing and gene expression assays. Applied and Environmental Microbiology, 78(24), 8611-8622.
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  PMID: 23042167;PMCID: PMC3502905;Abstract: Rhamnolipids have multiple potential applications as "green" surfactants for industry, remediation, and medicine. As a result, they have been intensively investigated to add to our understanding of their biosynthesis and improve yields. Several studies have noted that the addition of a fatty acid cosubstrate increases rhamnolipid yields, but a metabolic explanation has not been offered, partly because biosynthesis studies to date have used sugar or sugar derivatives as the carbon source. The objective of this study was to investigate the role of fatty acid cosubstrates in improving rhamnolipid biosynthesis. A combination of stable isotope tracing and gene expression assays was used to identify lipid precursors and potential lipid metabolic pathways used in rhamnolipid synthesis when fatty acid cosubstrates are present. To this end, we compared the rhamnolipids produced and their yields using either glucose alone or glucose and octadecanoic acid-d35 as cosubstrates. Using a combination of sugar and fatty acids, the rhamnolipid yield was significantly higher (i.e., doubled) than when glucose was used alone. Two patterns of deuterium incorporation (either 1 or 15 deuterium atoms) in a single Rha-C10 lipid chain were observed for octadecanoic acid-d35 treatment, indicating that in the presence of a fatty acid cosubstrate, both de novo fatty acid synthesis and β-oxidation are used to provide lipid precursors for rhamnolipids. Gene expression assays showed a 200- to 600-fold increase in the expression of rhlA and rhlB rhamnolipid biosynthesis genes and a more modest increase of 3- to 4-fold of the fadA β-oxidation pathway gene when octadecanoic acid was present. Taken together, these results suggest that the simultaneous use of de novo fatty acid synthesis and β-oxidation pathways allows for higher production of lipid precursors, resulting in increased rhamnolipid yields. © 2012, American Society for Microbiology.
• Favela, J. I., & Pemberton, J. E. (2011). Semi-transparent metal nanostructures as alternatives to transparent conducting oxides in organic photovoltaic devices. ACS National Meeting Book of Abstracts.
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  Abstract: Semi-transparent metallic, nanostructured, hole-selective contacts are intrinsically more conductive, more chemically stable, easier to modify, and significantly less costly than their transparent conductive oxide (TCO) counterparts traditionally used in organic photovoltaic (OPV) devices. In this work, gold nanowire, nanogrid and honeycomb nanostructures composed of a high work function materials were developed and explored as hole-selective contacts in OPVs. These structures show optical transparency and sheet resistance comparable to those of traditional TCOs that can be easily tuned by varying structure geometry, such as nanowire spacing or nanohole diameter. Results for power conversion efficiency and incident photon current efficiency (IPCE) will be reported for planar heterojunction OPV devices fabricated using these semi-transparent metallic nanostructures as hole-selective contacts and correlated to performance by conventional TCO based architectures.
• Huang, Y., & Pemberton, J. E. (2011). Fabrication of colloidal arrays by self-assembly of sub-100nm silica particles. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 377(1-3), 76-86.
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  Abstract: Self-assembly of sub-100. nm spherical silica nanoparticles into ordered, tightly packed three- and two-dimensional arrays was studied. Self-assembly by vertical evaporation was investigated for particles made by two methods: an optimized Stöber method recently reported from this laboratory and a modified reverse micelle method. Ordered, close-packed, two- and three-dimensional structures were formed with spherical nanoparticles made by the optimized Stöber method. Fast Fourier transforms of top-view scanning electron microscopy images document close-packed hexagonal packing for three-dimensional arrays consisting of particles as small as 50. nm. Ranges over which evaporation temperature and suspension particle concentration can be altered as strategies for improving packing quality of 50. nm particles have been defined. Self-assembly behavior that is distinct from that of larger particles (>200. nm) is observed for these sub-100. nm particles in that the ranges over which these variables can be altered to affect array packing quality are much smaller than for larger particles. In contrast, for particles made by the reverse micelle method, only structures with poor packing quality were obtained despite the fact that such particles are typically more uniform than those made by the Stöber method. These results provide clear evidence that, in addition to particle uniformity, other particle properties deriving from fabrication method play important roles in directing self-assembly of sub-100. nm particles. Finally, a rapid self-assembly method based on horizontal evaporation was used to produce close-packed three-dimensional structures of these sub-100. nm particles spanning several millimeters. Although these arrays are not as ordered as those made by vertical evaporation, the strategy reported herein allows tightly packed, crack-free arrays up to microns in thickness to be fabricated. A mechanism for self-assembly by this process is proposed. © 2011 Elsevier B.V.
• Pemberton, J. E., Matz, D. L., Schalnat, M. C., & Shaw, C. L. (2011). Interface evolution in the formation of low work function metal ohmic contacts on organic layers in photonic devices. ACS National Meeting Book of Abstracts.
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  Abstract: Low work function metals are commonly used as electron-selective ohmic contacts with electron transport layers in molecular photonic and electronic devices such as organic photovoltaics (OPVs), organic light emitting diodes (OLEDs) and organic field effect transistors (OFETs). Although the fundamental charge injection physics of such interfaces have been well described, the interfacial chemistry associated with these contacts is poorly understood and characterized. Efforts to characterize the chemistry of such interfaces using surface Raman spectroscopy have been undertaken in this laboratory. In this presentation, chemistry associated with evolution of the interfaces in these ohmic contacts will be explored for the low work function metals Ag, Al, Ca and Mg with solid state organic thin films including simple organic model systems, ordered forms of carbon, and polymeric systems. Implications for device performance will be considered.
• Schalnat, M. C., Hawkridge, A. M., & Pemberton, J. E. (2011). Raman spectroscopy of the reaction of thin films of solid-state benzene with vapor-deposited Ag, Mg, and Al. Journal of Physical Chemistry C, 115(28), 13717-13724.
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  Abstract: Thin films of solid-state benzene at 30 K were reacted with small quantities of vapor-deposited Ag, Mg, and Al under ultrahigh vacuum, and products were monitored using surface Raman spectroscopy. Although Ag and Mg produce small amounts of metal-benzene adduct products, the resulting Raman spectra are dominated by surface enhancement of the normal benzene modes from metallic nanoparticles suggesting rapid Ag or Mg metallization of the film. In contrast, large quantities of Al adduct products are observed. Vibrational modes of the products in all three systems suggest adducts that are formed through a pathway initiated by an electron transfer reaction. The difference in reactivity between these metals is ascribed to differences in ionization potential of the metal atoms; ionization potential values for Ag and Mg are similar but larger than that for Al. These studies demonstrate the importance of atomic parameters, such as ionization potential, in solid-state metal-organic reaction chemistry. © 2011 American Chemical Society.
• Baughman, K. F., Maier, R. M., Norris, T. A., Beam, B. M., Mudalige, A., Pemberton, J. E., & Curry, J. E. (2010). Evaporative deposition patterns of bacteria from a sessile drop: Effect of changes in surface wettability due to exposure to a laboratory atmosphere. Langmuir, 26(10), 7293-7298.
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  PMID: 20405926;Abstract: Evaporative deposition from a sessile drop is a simple and appealing way to deposit materials on a surface. In this work, we deposit living, motile colloidal particles (bacteria) on mica from drops of aqueous solution. We show for the first time that it is possible to produce a continuous variation in the deposition pattern from ring deposits to cellular pattern deposits by incremental changes in surface wettability which we achieve by timed exposure of the mica surface to the atmosphere. We show that it is possible to change the contact angle of the drop from less than 5° to near 20° by choice of atmospheric exposure time. This controls the extent of drop spreading, which in turn determines the architecture of the deposition pattern. © 2010 American Chemical Society.
• Huang, Y., & Pemberton, J. E. (2010). Synthesis of uniform, spherical sub-100nm silica particles using a conceptual modification of the classic LaMer model. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 360(1-3), 175-183.
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  Abstract: A strategy for production of monodisperse spherical sub-100nm silica particles is demonstrated based on application of a conceptual modification of the classic LaMer model to the Stöber process. Strategies for control of particle properties, including particle size, size distribution, and shape are proposed. The approach demonstrated herein starts from a small number of test experiments and then focuses on adjusting the reaction conditions that control undesirable particle properties of the resulting particles while leaving conditions that dictate desirable properties unchanged. This strategy reduces considerably the number of test experiments required for synthesis of uniform and spherical sub-100nm silica particles compared to other reported methods that utilize a large number of test experiments to define optimized reaction conditions. Synthesis of particles in the size range of 27-100nm with relative standard deviations in size of
• Kumaran, N., Minch, B. A., Veneman, P. A., Mudalige, A., Pemberton, J. E., O'Brien, D. F., & Armstrong, N. R. (2010). "Self-Organized Thin Films of Hydrogen-Bonded Phthalocyanines: Characterization of Structure and Electrical Properties on Nanometer Length Scales. Chemistry of Materials, 22, 2491-2501.
• Neilson, J. W., Zhang, L., Veres-Schalnat, T. A., Chandler, K. B., Neilson, C. H., Crispin, J. D., Pemberton, J. E., & Maier, R. M. (2010). Cadmium effects on transcriptional expression of rhlB/rhlC genes and congener distribution of monorhamnolipid and dirhamnolipid in Pseudomonas aeruginosa IGB83. Applied Microbiology and Biotechnology, 88(4), 953-963.
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  PMID: 20706835;Abstract: While variable production of the biosurfactant, rhamnolipid, by Pseudomonas aeruginosa has been shown to be dependent on growth conditions, no research has evaluated potential relationships between rhamnolipid production and the presence of heavy metals. The current investigation evaluates the influence of Cd2+ on rhamnolipid synthesis. Cultures grown in the presence of 0.45 and 0.89 mM Cd2+ were monitored for rhlB/rhlC expression, rhamnolipid yield, and the ratio of monorhamnolipid (RL1) and dirhamnolipid (RL2) produced. Results show a Cdinduced enhancement of rhlB expression in mid-stationary phase (53 h). In addition, sustained production of rhamnolipid through late stationary growth phase (96 h) was observed for Cd-amended cultures, unlike Cd-free control cultures that ceased rhamnolipid production by midstationary growth phase. Most significant was an observed increase in the ratio of RL2 to RL1 congeners produced by cultures grown in the presence of Cd2+. Previous results have shown that the complexation constant for RL2-Cd is several orders of magnitude larger than that of RL1-Cd thus the preferential production of RL2 in the presence of Cd2+ impacts its bioavailability and toxicity both for the cell and in the surrounding environment. © Springer-Verlag 2010.
• Schalnat, M. C., & Pemberton, J. E. (2010). Comparison of a fluorinated aryl thiol self-assembled monolayer with its hydrogenated counterpart on polycrystalline Ag substrates. Langmuir, 26(14), 11862-11869.
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  PMID: 20552959;Abstract: The effects of perfluorination of aryl thiols on surface coverage, surface electronic properties, and molecular orientation of self-assembled monolayers of thiophenol (TP) and pentafluorothiophenol (F5TP) on polycrystalline Ag were evaluated using linear sweep voltammetry, ultraviolet photoelectron spectroscopy (UPS), and surface Raman spectroscopy, respectively. Electrochemical reductive desorption by linear sweep voltammetry indicates a surface coverage for the TP monolayer of (5.07 ± 1.29) × 10 -10 mol/cm2, equating to a molecular area of 32.8 ± 8.3 Å2, and a surface coverage for the F5TP monolayer of (1.95 ± 0.59) × 10-10 mol/cm2, equating to an area of 85.2 ± 25.8 Å 2/ molecule. TP-modified Ag exhibits a change in work function (δφ) of -0.64 eV relative to bare Ag, whereas F5TP modified Ag exhibits a δφ of +0.54 eV relative to bare Ag. Quantitative analysis of the UPS and reductive desorption results yields molecular pictures of the proposed interfaces with TP molecules tilted
• Alloway, D. M., Graham, A. L., Yang, X., Mudalige, A., Wysocki, V. H., Pemberton, J. E., Lee, T. R., Colorado, R., Wysocki, R. J., & Armstrong, N. R. (2009). Tuning the Effective Work Function of Gold and Silver using Alkanethiols: Varying Surface Composition Through Dilution and Choice of Terminal Groups. Journal of Physical Chemistry C, 113, 20328-20334.
• Davis, R. J., & Pemberton, J. E. (2009). Surface Raman spectroscopy of the interface of tris-(8-hydroxyquinoline) aluminum with Mg. Journal of the American Chemical Society, 131(29), 10009-10014.
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  PMID: 19583253;Abstract: Surface Raman spectroscopy in ultrahigh vacuum is used to interrogate interfaces formed between tris-(8-hydroxyquinoline) aluminum (Alq3) and vapor-deposited Mg. The Raman spectral results for deposition of Mg mass thicknesses between 5 and 20 Å indicate formation of a complex interfacial region composed primarily of Mg-Alq3 adducts and small-grained amorphous or nanocrystalline graphite, the presence of which may have a significant effect on the electronic properties of this metal-organic interface. The observed shifts in νring, ν(C-N), ν(Al-N), and ν(Al-O) modes along with the appearance of ν(Mg-C) and ν(Mg-O) modes suggest a structure for the Mg-Alq3 adduct in which Mg is bound to the O and C atoms of Alq3. In addition, several intense, broad modes are observed that are consistent with partial graphitization of the Alq 3 film. © 2009 American Chemical Society.
• Davis, R. J., & Pemberton, J. E. (2009). Surface raman spectroscopy of chemistry at the tris(8-hydroxyquinoline) aluminum/Ca interface. Journal of Physical Chemistry A, 113(16), 4397-4402.
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  PMID: 19371117;Abstract: Surface Raman spectroscopy in ultrahigh vacuum is used to interrogate interfaces formed between tris(8- hydroxyquinoline) aluminum (Alq3) and vapor-deposited Ca. Vapor deposition of Ca onto Alq3 films results in the appearance of new vibrational modes consistent with the formation of a Ca-Alq3 adduct in which Ca is bound through the O of Alq3. In addition, the graphitic carbon is observed to form with the deposition of Ca onto Alq3 films. The frequency and relative peak height ratios of graphitic D-band and G-band observed are consistent with more disordered sp3-type carbon forming upon partial decomposition of the organic film. © 2009 American Chemical Society.
• Keng, P. Y., Shim, I., Kim, B. Y., Sahoo, R., Veneman, P. E., Armstrong, N. R., Yoo, H., Pemberton, J. E., Bull, M. M., Griebel, J. J., Ratcliff, E. L., Nebesny, K. W., & Pyun, D. (2009). Colloidal Polymerization of Polymer Coated Ferromagnetic Nanoparticles into Cobalt Oxide Nanowires. ACS Nano, 3, 3143-3157.
• Macech, P., & Pemberton, J. E. (2009). Passivation of pinhole defect microelectrode arrays in ultrathin silica films immobilized on gold substrates. Thin Solid Films, 517(18), 5399-5403.
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  Abstract: Nanoscopic defects present in ultrathin (~ 6 nm) silica films covalently attached to gold substrates through a gold oxide layer exhibit a voltammetric response consistent with a random array of ultramicroelectrodes. These pinholes can be passivated via electrochemical polymerization of phenol to create insulating poly(phenylene) oxide plugs as documented by atomic force microscopy and infrared reflectance-absorbance spectroscopy. Passivation of pinholes is ~ 99.5% complete after 550 voltammetric cycles of oxidative electropolymerization. © 2009 Elsevier B.V. All rights reserved.
• Pemberton, J., Davis, R. J., & Pemberton, J. E. (2009). Surface Raman spectroscopy of chemistry at the tris(8-hydroxyquinoline) aluminum/Ca interface. The journal of physical chemistry. A, 113(16).
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  Surface Raman spectroscopy in ultrahigh vacuum is used to interrogate interfaces formed between tris(8-hydroxyquinoline) aluminum (Alq(3)) and vapor-deposited Ca. Vapor deposition of Ca onto Alq(3) films results in the appearance of new vibrational modes consistent with the formation of a Ca-Alq(3) adduct in which Ca is bound through the O of Alq(3.) In addition, the graphitic carbon is observed to form with the deposition of Ca onto Alq(3) films. The frequency and relative peak height ratios of graphitic D-band and G-band observed are consistent with more disordered sp(3)-type carbon forming upon partial decomposition of the organic film.
• Pemberton, J., Davis, R. J., & Pemberton, J. E. (2009). Surface Raman spectroscopy of the interface of tris-(8-hydroxyquinoline) aluminum with Mg. Journal of the American Chemical Society, 131(29).
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  Surface Raman spectroscopy in ultrahigh vacuum is used to interrogate interfaces formed between tris-(8-hydroxyquinoline) aluminum (Alq(3)) and vapor-deposited Mg. The Raman spectral results for deposition of Mg mass thicknesses between 5 and 20 A indicate formation of a complex interfacial region composed primarily of Mg-Alq(3) adducts and small-grained amorphous or nanocrystalline graphite, the presence of which may have a significant effect on the electronic properties of this metal-organic interface. The observed shifts in nu(ring), nu(C-N), nu(Al-N), and nu(Al-O) modes along with the appearance of nu(Mg-C) and nu(Mg-O) modes suggest a structure for the Mg-Alq(3) adduct in which Mg is bound to the O and C atoms of Alq(3). In addition, several intense, broad modes are observed that are consistent with partial graphitization of the Alq(3) film.
• Schalnat, M. C., & Pemberton, J. E. (2009). Investigation of interfacial interactions of solid-state benzene with low work function metals by Raman spectroscopy and mass spectrometry. ACS National Meeting Book of Abstracts.
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  Abstract: Extensive previous studies have been performed to fully understand and optimize charge injection across metal-organic interfaces in organic light emitting diodes (OLEDs) and organic photovoltaics (OPVs). However, the interpretation of these studies is complicated at best. Therefore, in order to fully understand the chemistry at these junctions, it is essential to understand the fundamental solid state interactions between simple "model" organic molecules and common electrode metals. Many of the common organic molecules that are presently being used in these devices are comprised of aryl-containing moieties, leading to the selection of benzene as the "model" molecule in the current research. Thin solid benzene films were deposited under ultrahigh vacuum conditions and reacted with increasing amounts of Al, Ca, Mg, and Ag. Raman spectroscopy was used to investigate vibrational modes of products formed, while mass spectrometry was used to determine the stoichiometry and thermal stability of metal-organic complexes. Implications of these results for low work function metal-organic interfaces in devices will be discussed.
• Davis, R. J., & Pemberton, J. E. (2008). Investigation of the interfaces of tris-(8-hydroxyquinoline) aluminum with Ag and Al using surface Raman spectroscopy. Journal of Physical Chemistry C, 112(11), 4364-4371.
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  Abstract: Surface Raman spectroscopy in ultrahigh vacuum is used to interrogate interfaces formed between tris-(8-hydroxyquinoline) aluminum (Alq3) and vapor-deposited Ag and A1. Vapor deposition of Ag onto Alq3 films results in preservation of the Alq3 structure with evolution of simple surface enhancement of Alq3 spectral intensities. Changes in the relative intensities of ring breathing and ring stretching modes of Alq 3 upon deposition of Ag are consistent with weak interaction of Ag with the conjugated ring of the ligand. In contrast, vapor deposition of Al onto Alq3 films results in the appearance of new vibrational modes, but only for Al coverages > 10 Å mass thickness, consistent with the formation of an Al-Alq3 adduct. At these coverages, slight surface enhancement of spectral intensities is also observed along with growth of several broad modes consistent with partial graphitization of the organic film. © 2008 American Chemical Society.
• Heier, S. T., Johnson, K. E., Mudalige, A., Tiani, D. J., Reid, V. R., & Pemberton, J. E. (2008). Infrared reflectance-absorbance spectroscopy of thin films formed by forced dewetting of solid-fluid interfaces. Analytical Chemistry, 80(21), 8012-8019.
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  PMID: 18826245;Abstract: An infrared reflectance-absorbance spectroscopy method for characterizing the ultrathin fluid film retained on a surface upon forced dewetting from a fluid has been developed for investigation of interfacial molecular structure at reflective substrates. This report details the optical considerations and constraints necessary to acquire IR spectral data from nanometer-thick films retained upon forced dewetting of a solid substrate from a fluid into a vapor-saturated environment. The feasibility of this method is demonstrated through successful spectral acquisition from Ag surfaces modified with 11-mercaptoundecanol forcibly dewet from water. The IR spectral results clearly illustrate that information is acquired only from the interfacial region with no contribution from the bulk liquid. Residual layer thicknesses calculated from IR absorbance values are substantiated by ellipsometry. The spectra make clear that the molecular structure of the residual layer is distinctly different from that of the bulk liquid, confirming that this method is viable for interfacial structure elucidation of thin fluid films at a variety of solid substrates. © 2008 American Chemical Society.
• Liao, Z., & Pemberton, J. E. (2008). Structure-function relationships in high-density docosylsilane bonded stationary phases by Raman spectroscopy and comparison to octadecylsilane bonded stationary phases: Effects of aromatic compounds. Journal of Chromatography A, 1193(1-2), 60-69.
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  PMID: 18448107;Abstract: The effects of four aromatic compounds on alkyl chain conformational order for a series of high-density docosylsilane (C22) stationary phases with surface coverage ranging from 3.61 to 6.97 μmol/m2 are investigated using Raman spectroscopy. Aromatic compounds studied include benzene-d6, toluene-d8, aniline-d7 and anisole-d8. In general, these aromatic solvents decrease the conformational order of the C22 phases relative to air suggesting partitioning of the aromatics into the alkyl chains of these stationary phases. Changes in alkyl chain conformational order are linearly dependent on the solvent hydrophobicity parameter, log Kow, and are also dependent on stationary phase properties (i.e. polymerization method and surface coverage). A comparison is made between C22 and C18 bonded phase systems. The conformational order of the alkyl chains in a mixed solute/mobile phase system is also studied using 80% methanol/water as the mobile phase and aniline-d7, anisole-d8 or toluene-d8 as solutes. Collectively, the Raman spectroscopic evidence at the molecular level suggests interaction of these aromatic species with the bonded alkyl chains through partitioning. © 2008 Elsevier B.V. All rights reserved.
• Liao, Z., & Pemberton, J. E. (2008). Structure-function relationships in high-density docosylsilane bonded stationary phases by Raman spectroscopy and comparison to octadecylsilane bonded stationary phases: Effects of common solvents. Analytical Chemistry, 80(8), 2911-2920.
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  PMID: 18336011;Abstract: The effects of common solvents on alkyl chain conformational order in a series of high-density C22 stationary phases with surface coverage ranging from 3.61 to 6.97 μmol/m2 are investigated by Raman spectroscopy. Conformational order is evaluated using the intensity ratio of the antisymmetric and symmetric v(CH2) modes as well as the frequencies at which these Raman bands are observed. Solvents studied include methanol-d4, acetonitrile-d3, water-d2, toluene-d8, chloroform-d. and benzene-d6. Alkyl chain conformational order and, hence, solvation of the stationary phase, is dependent on the Gibbs free energy change for these molecules at infinite dilution in hexadecane (ΔG HD○), as well as stationary-phase properties (polymerization method and surface coverage). In general, polar solvents increase slightly the conformational order of these C22 stationary phases, while non-polar solvents decrease conformational order. A comparison is made between C22 and C18 bonded-phase systems to further understand the role of alkyl chain length on solvent-stationary phase interactions. The change in alkyl chain conformational order induced by solvent is also compared to that induced by temperature, which provides insight into the effect of chromatographic conditions on stationary-phase shape selectivity, an important application of these materials. © 2008 American Chemical Society.
• Paniagua, S. A., Hotchkiss, P. J., Jones, S. C., Marder, S. R., Mudalige, A., Marrikar, F. S., Pemberton, J. E., & Armstrong, N. R. (2008). Phosphonic Acid Modification of Indium-Tin Oxide Electrodes: Combined XPS/UPS/Contact Angle Studies. Journal of Physical Chemistry C, 112, 7809-7817.
• Pasilis, S. P., & Pemberton, J. E. (2008). Spectroscopic investigation of uranyl(VI) and citrate coadsorption to Al₂O₃. Geochimica et Cosmochimica Acta, 72(2), 277-287.
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  Abstract: ATR-FTIR spectroscopy is used to understand the adsorption of uranyl-citrate complexes to Al2O3. Spectral data indicate that uranyl-citrate complexes partially dissociate upon adsorption, allowing full or partial hydrolysis of the uranyl ion. Kads values determined for free citrate adsorption are similar to those for citrate in uranyl-citrate complexes, indicating that the complexation of uranyl by citrate does not significantly affect the ability of citrate to bond with the surface. The isotherm data also indicate enhanced citrate adsorption to Al2O3 in the presence of uranyl, suggesting that uranyl may be the central link between two citrate ligands, and that uranyl is associated with the surface through a bridging citrate ligand. Finally, uranyl-citrate complexes interact with citrate adsorbed to Al2O3 through outer sphere interactions. © 2007 Elsevier Ltd. All rights reserved.
• Pemberton, J., Heier, S. T., Johnson, K. E., Mudalige, A., Tiani, D. J., Reid, V. R., & Pemberton, J. E. (2008). Infrared reflectance-absorbance spectroscopy of thin films formed by forced dewetting of solid-fluid interfaces. Analytical chemistry, 80(21).
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  An infrared reflectance-absorbance spectroscopy method for characterizing the ultrathin fluid film retained on a surface upon forced dewetting from a fluid has been developed for investigation of interfacial molecular structure at reflective substrates. This report details the optical considerations and constraints necessary to acquire IR spectral data from nanometer-thick films retained upon forced dewetting of a solid substrate from a fluid into a vapor-saturated environment. The feasibility of this method is demonstrated through successful spectral acquisition from Ag surfaces modified with 11-mercaptoundecanol forcibly dewet from water. The IR spectral results clearly illustrate that information is acquired only from the interfacial region with no contribution from the bulk liquid. Residual layer thicknesses calculated from IR absorbance values are substantiated by ellipsometry. The spectra make clear that the molecular structure of the residual layer is distinctly different from that of the bulk liquid, confirming that this method is viable for interfacial structure elucidation of thin fluid films at a variety of solid substrates.
• Pemberton, J., Liao, Z., & Pemberton, J. E. (2008). Structure-function relationships in high-density docosylsilane bonded stationary phases by Raman spectroscopy and comparison to octadecylsilane bonded stationary phases: effects of aromatic compounds. Journal of chromatography. A, 1193(1-2).
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  The effects of four aromatic compounds on alkyl chain conformational order for a series of high-density docosylsilane (C22) stationary phases with surface coverage ranging from 3.61 to 6.97 micromol/m2 are investigated using Raman spectroscopy. Aromatic compounds studied include benzene-d6, toluene-d8, aniline-d7 and anisole-d8. In general, these aromatic solvents decrease the conformational order of the C22 phases relative to air suggesting partitioning of the aromatics into the alkyl chains of these stationary phases. Changes in alkyl chain conformational order are linearly dependent on the solvent hydrophobicity parameter, log K ow, and are also dependent on stationary phase properties (i.e. polymerization method and surface coverage). A comparison is made between C22 and C18 bonded phase systems. The conformational order of the alkyl chains in a mixed solute/mobile phase system is also studied using 80% methanol/water as the mobile phase and aniline-d7, anisole-d8 or toluene-d8 as solutes. Collectively, the Raman spectroscopic evidence at the molecular level suggests interaction of these aromatic species with the bonded alkyl chains through partitioning.
• Pemberton, J., Liao, Z., & Pemberton, J. E. (2008). Structure-function relationships in high-density docosylsilane bonded stationary phases by Raman spectroscopy and comparison to octadecylsilane bonded stationary phases: effects of common solvents. Analytical chemistry, 80(8).
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  The effects of common solvents on alkyl chain conformational order in a series of high-density C22 stationary phases with surface coverage ranging from 3.61 to 6.97 micromol/m2 are investigated by Raman spectroscopy. Conformational order is evaluated using the intensity ratio of the antisymmetric and symmetric nu(CH2) modes as well as the frequencies at which these Raman bands are observed. Solvents studied include methanol-d4, acetonitrile-d3, water-d2, toluene-d8, chloroform-d. and benzene-d6. Alkyl chain conformational order and, hence, solvation of the stationary phase, is dependent on the Gibbs free energy change for these molecules at infinite dilution in hexadecane (DeltaG(o)HD), as well as stationary-phase properties (polymerization method and surface coverage). In general, polar solvents increase slightly the conformational order of these C22 stationary phases, while nonpolar solvents decrease conformational order. A comparison is made between C22 and C18 bonded-phase systems to further understand the role of alkyl chain length on solvent-stationary phase interactions. The change in alkyl chain conformational order induced by solvent is also compared to that induced by temperature, which provides insight into the effect of chromatographic conditions on stationary-phase shape selectivity, an important application of these materials.
• Pemberton, J., Tiani, D. J., Yoo, H., Mudalige, A., & Pemberton, J. E. (2008). Interfacial structure in thin water layers formed by forced dewetting on self-assembled monolayers of omega-terminated alkanethiols on Ag. Langmuir : the ACS journal of surfaces and colloids, 24(23).
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  A method for the spectroscopic characterization of interfacial fluid molecular structure near solid substrates is reported. The thickness and interfacial molecular structure of residual ultrathin D20 films remaining after forced dewetting on alkanethiolate self-assembled monolayers (SAMs) of 11 1-mercaptoundecanoic acid (11-MUA), 11-mercaptoundecanol (11-MUD), and undecanethiol (UDT) on Ag are investigated using ellipsometry and surface Raman spectroscopy. The residual film thickness left after withdrawal is greater on hydrophilic SAMs than on hydrophobic SAMs. This behavior is rationalized on the basis of differing degrees of fluid slip within the interfacial region due to different interfacial molecular structure. The v(O-D) regions of surface Raman spectra clearly indicate unique interfacial molecular properties within these films that differ from bulk D20. Although the residual films are created by shear forces and Marangoni flow at the three-phase line during the forced dewetting process, the nature of the films sampled optically must also be considered from the standpoint of thin film stability after dewetting. Thus, the resulting D20 films exist in vastly different morphologies depending on the nature of the water-SAM interactions. Residual D20 is proposed to exist as small nanodroplets on UDT surfaces due tospontaneous rupture of the film after dewetting. In contrast, on 11-MUD and 11-MUA surfaces, these films exist in a metastable state that retains their conformal nature on the underlying modified surface. Analysis of the peak intensity ratios of the so-called "ice-like" to "liquid-like" v(O-D) modes suggests more ice-like D20 character near 11-MUD surfaces, but more liquid-like character near 11-MUA and UDT surfaces. The creation of residual ultrathin films by forced dewetting is thus demonstrated to be a powerful method for characterizing interfacial molecular structure of fluids near a solid substrate under ambient conditions of temperature and pressure.
• Saini, H. S., Barragán-Huerta, B. E., Lebrón-Paler, A., Pemberton, J. E., Vázquez, R. R., Burns, A. M., Marron, M. T., Seliga, C. J., A., A., & Maier, R. M. (2008). Efficient purification of the biosurfactant viscosin from Pseudomonas libanensis strain M9-3 and its physicochemical and biological properties. Journal of Natural Products, 71(6), 1011-1015.
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  PMID: 18471020;Abstract: Viscosin (1), an effective surface-active cyclic lipopeptide, was efficiently recovered from Pseudomonas libanensis M9-3 with a simple purification protocol. A major pigment also obtained during this process was identified as phenazine-1-carboxylic acid. The critical micelle concentration (cmc) of viscosin was determined to be 54 mg L-1, and the minimum surface tension between air and water at the cmc was 28 mN m-1. Viscosin forms stable emulsions even at low concentrations (7.5 mg L -1), and the conditional stability constant for a cadmium - viscosin complex was determined to be 5.87. The physicochemical properties measured for viscosin are similar to other well-studied biosurfactants such as rhamnolipid and surfactin. Viscosin inhibited migration of the metastatic prostate cancer cell line, PC-3M, without visible toxicity. These properties suggest the potential of viscosin in environmental and biomedical applications. © 2008 American Chemical Society and American Society of Pharmacognosy.
• Tiani, D. J., Yoo, H., Mudalige, A., & Pemberton, J. E. (2008). Interfacial structure in thin water layers formed by forced dewetting on Self-Assembled monolayers of Ω-Terminated alkanethiols on ag. Langmuir, 24(23), 13483-13489.
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  PMID: 18986189;Abstract: A method for the spectroscopic characterization of interfacial fluid molecular structure near solid substrates is reported. The thickness and interfacial molecular structure of residual ultrathin D 2O films remaining after forced dewetting on alkanethiolate self-assembled monolayers (SAMs) of 11-mercaptoundecanoic acid (11-MUA), 11- mercaptoundecanol (11-MUD), and undecanethiol (UDT) on Ag are investigated using ellipsometry and surface Raman spectroscopy. The residual film thickness left after withdrawal is greater on hydrophilicSAMsthan on hydrophobic SAMs. This behavior is rationalized on the basis of differing degrees of fluid slip within the interfacial region due to different interfacial molecular structure. The υ(O-D) regions of surface Raman spectra clearly indicate unique interfacial molecular properties within these films that differ from bulk D 2O. Although the residual films are created by shear forces and Marangoni flow at the three-phase line during the forced dewetting process, the nature of the films sampled optically must also be considered from the standpoint of thin film stability after dewetting. Thus, the resulting D 2O films exist in vastly different morphologies depending on the nature of the water-SAM interactions. Residual D 2O is proposed to exist as small nanodroplets on UDT surfaces due to spontaneous rupture of the film after dewetting. In contrast, on 11-MUD and 11-MUA surfaces, these films exist in a metastable state that retains their conformal nature on the underlying modified surface. Analysis of the peak intensity ratios of the so-called "ice-like" to "liquid-like" ?(O-D) modes suggests more ice-like D2O character near 11-MUD surfaces, but more liquid-like character near 11-MUA and UDT surfaces. The creation of residual ultrathin films by forced dewetting is thus demonstrated to be a powerful method for characterizing interfacial molecular structure of fluids near a solid substrate under ambient conditions of temperature and pressure.© 2008 American Chemical Society.
• Zangmeister, C. D., Davis, R. J., Mrozek, P., & Pemberton, J. E. (2008). Reduction of nitric acid on Ag in ultrahigh vacuum: A Raman spectroscopic investigation. Surface Science, 602(14), 2395-2401.
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  Abstract: The reduction of HNO3 on Ag as a function of temperature in ultrahigh vacuum (UHV) is studied using Raman spectroscopy and thermal desorption-mass spectrometry (TDMS). Thin layers of molecular HNO3 are stable on the surface below 150 K, but are spontaneously reduced above 150 K with concomitant time-dependent partial desorption of products. The asymmetric nitric oxide dimer, NONO, is observed as the sole reduction product that remains on the surface based on its distinctive Raman spectral signature. The mechanism of NONO formation from HNO3 is proposed to occur through a multistep reduction of HNO3 on the Ag surface starting from NO3- and proceeding stepwise through NO2 and NO2- to NO, followed by combination to form NONO in a process catalyzed by a Lewis acid, oxidized Ag species. Desorption of the majority of surface species is largely complete by 210 K. © 2008 Elsevier B.V. All rights reserved.
• Bowles, S. E., Wei, W. u., Kowalewski, T., Schalnat, M. C., Davis, R. J., Pemberton, J. E., Shim, I., Korth, B. D., & Pyun, J. (2007). Magnetic assembly and pyrolysis of functional ferromagnetic colloids into one-dimensional carbon nanostructures. Journal of the American Chemical Society, 129(28), 8694-8695.
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  PMID: 17589997;Abstract: A novel synthetic route to functionalize and magnetically assemble ferromagnetic colloids into one-dimensional (1-D) carbon nanostructures is reported. The synthesis of ferromagnetic cobalt nanoparticles with polyacrylonitrile (PAN) shells was achieved by ligand exchange of PAN onto preformed polystyrene-coated ferromagnetic cobalt nanoparticles. PAN-coated ferromagnetic nanoparticles (PAN-CoNPs) were then cast onto supporting surfaces from N,N-dimethylformamide (DMF) in the presence of an external magnetic field and pyrolyzed to form 1-D carbon nanoparticle chains spanning microns in length. Atomic force microscopy, field emission scanning electron microscopy, Raman spectroscopy, vibrating sample magnetometry, and X-ray diffraction were used to confirm the preparation of these 1-D hybrid nanostructures. This versatile methodology provides an alternative approach to prepare 1-D carbon materials using soluble precursors that can be magnetically directed and organized. Copyright © 2007 American Chemical Society.
• Macech, P., & Pemberton, J. E. (2007). Ultrathin silica films immobilized on gold supports: Fabrication, characterization, and modification. Langmuir, 23(19), 9816-9822.
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  PMID: 17691827;Abstract: A novel method for covalent attachment of ultrathin silica films (thickness < 10 nm) to gold substrates is reported. Silica layers were prepared using spin-coating of sol-gel precursor solutions onto gold substrates that were cleaned and oxidized using UV photo-oxidation in an ozone atmosphere. The gold oxide layer resulting from this process acts as a wetting control and adhesive agent for the ultrathin silica layer. Control of silica layer thickness between ~6 and 60 nm through modification of precursor solution composition or by repetitive deposition is demonstrated. Films were characterized using infrared spectroscopy, ellipsometry, atomic force microscopy, and cyclic voltammetry. For the standard deposition parameters developed here, films were determined to be 5.5 ± 0.75 nm thick, and were stable in aqueous solutions ranging in pH from 2 to 10 for at least 30 min. Films contained nanoscopic defects with radii of ≤ 2 μm in all cases, at a density of 1.6 defects per 10 μm × 10 μm region, with a weighted average defect radius of 200 nm. This array of defects was shown to exhibit a voltammetric response consistent with an ultramicroelectrode array. Finally, ultrathin silica films were also modified with self-assembled monolayers of octadecylsilane, demonstrating the surface chemistry of bulk silica. © 2007 American Chemical Society.
• Marrikar, F. S., Brumbach, M., Evans, D. H., Lebron-Paler, A., Pemberton, J. E., Wysocki, R. J., & Armstrong, N. R. (2007). Modification of Indium-Tin Oxide Electrodes with Thiophene Copolymer Thin Films: Optimizing Electron Transfer to Solution Probe Molecules. Langmuir, 23, 1530-1542.
• Mudalige, A., & Pemberton, J. E. (2007). Raman spectroscopy of glycerol/D₂O solutions. Vibrational Spectroscopy, 45(1), 27-35.
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  Abstract: Raman spectra of neat glycerol, neat D2O, and glycerol/D2O solutions with glycerol mole fractions (XG) of 0.00, 0.02, 0.12 and 0.32 and 1.00 are presented. Vibrational assignments are discussed for the bands observed in the 1000-1600 and 2000-3700 cm-1 spectral regions. Upon dilution of neat glycerol with D2O, glycerol hydrogen-bonds with D2O through its oxygen atoms as hydrogen-bond acceptors. With progressive glycerol dilution, D2O breaks the dimers and higher oligomers present in neat glycerol to form glycerol monomers. D2O molecules in the XG 0.02 solution are in an environment similar to that of neat D2O due to minimal perturbation of the D2O network. The absence of bands due to weakly hydrogen-bonded D2O in the XG 0.12 solution suggests that most D2O are more strongly hydrogen-bonded than in neat D2O as would occur in D2O clusters. D2O in XG 0.32 solutions are in a unique environment in that they lose their hydrogen-bonding network completely, mixing into the solution as monomers. © 2007 Elsevier B.V. All rights reserved.
• Pemberton, J., Macech, P., & Pemberton, J. E. (2007). Ultrathin silica films immobilized on gold supports: fabrication, characterization, and modification. Langmuir : the ACS journal of surfaces and colloids, 23(19).
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  A novel method for covalent attachment of ultrathin silica films (thickness
• Pemberton, J., Robertson, J. W., Tiani, D. J., & Pemberton, J. E. (2007). Underpotential deposition of thallium, lead, and cadmium at silver electrodes modified with self-assembled monolayers of (3-mercaptopropyl)trimethoxysilane. Langmuir : the ACS journal of surfaces and colloids, 23(8).
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  Investigation of the underpotential deposition (UPD) of three metals-Tl, Pb, and Cd-on Ag surfaces modified with self-assembled monolayers (SAMs) of (3-mercaptopropyl)trimethoxysilane (3MPT) is reported. On the basis of the observation of negative potential shifts for their UPD processes, Tl and Pb undergo UPD directly on the underlying Ag surface by insertion between the Ag-S bond. This process is proposed to occur by penetration of the 3MPT monolayer by hydrated metal ions through spaces in six-membered siloxane rings that form at the terminus of the 3MPT layer after hydrolysis and condensation. In contrast, Cd does not undergo similarly facile UPD at 3MPT-modified Ag electrodes due to a hydrated ion size too large to fit through these openings. The voltammetric evidence that suggests that the hydrated metal cation size, as described by the Stokes diameter, is the primary determinant of Ag electrode accessibility for UPD through the cross-linked 3MPT layer is further supported by molecular mechanics energy minimization computations of six-membered siloxane rings on each of the three low-index faces of Ag. Finally, the 3MPT monolayer is shown to be exceptionally stable to repeated UPD/stripping cycles of Tl and Pb in contrast to SAMs of similar thickness formed from normal alkanethiols.
• Schulmeyer, T., Paniagua, S. A., Veneman, P. A., Jones, S. C., Hotchkiss, P. J., Mudalige, A., Pemberton, J. E., Marder, S. R., & Armstrong, N. R. (2007). Modification of BaTiO3 Thin Films: Adjustment of the Effective Surface Work Function. Journal of Materials Chemistry, 17, 4563-4570.
• Somogyi, Á., Pasilis, S. P., & Pemberton, J. E. (2007). Electrospray ionization of uranyl-citrate complexes: Adduct formation and ion-molecule reactions in 3D ion trap and ion cyclotron resonance trapping instruments. International Journal of Mass Spectrometry, 265(2-3), 281-294.
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  Abstract: Results presented here demonstrate the usefulness of electrospray ionization and gas-phase ion-molecule reactions to predict structural and electronic differences in complex inorganic ions. Electrospray ionization of uranyl citrate solutions generates positively and negatively charged ions that participate in further ion-molecule reactions in 3D ion trap and FT-ICR mass analyzers. Most ions observed are derived from the major solution uranyl-citrate complexes and involve species of {(UO2)2Cit2}2-, (UO2)3Cit2, and {(UO2)3Cit3}3-, where Cit indicates the citrate trianion, C6H5O73-. In a 3D ion trap operated at relatively high pressure, complex adducts containing solvent molecules, alkali and ammonium cations, and nitrate or chloride anions are dominant, and proton/alkali cation (Na+, K+) exchange is observed for up to six exchangeable protons in an excess of alkali cations. Adduct formation in a FT-ICR cell that is operated at lower pressures is less dominant, and direct detection of positive and negative ions of the major solution complexes is possible. Multiply charged ions are also detected, suggesting the presence of uranium in different oxidation states. Changes in uranium oxidation state are detected by He-CID and SORI-CID fragmentation, and certain fragments undergo association reactions in trapping analyzers, forming "exotic" species such as [(UO2)4O3]-, [(UO2)4O4]-, and [(UO2)4O5]-. Ion-molecule reactions with D2O in the FT-ICR cell indicate substantial differences in H/D exchange rate and D2O accommodation for different ion structures and charge states. Most notably, the positively charged ions [H2(UO2)2Cit2(H)]+ and [(UO2)2(Cit)]+ accommodate two and three D2O molecules, respectively, which reflects well the structural differences, i.e., tighter uranyl-citrate coordination in the former ion than in the latter. The corresponding negatively charged ions accommodate zero or two D2O molecules, which can be rationalized using suggested solution phase structures and charge state distributions.
• W., J., Tiani, D. J., & Pemberton, J. E. (2007). Underpotential deposition of thallium, lead, and cadmium at silver electrodes modified with self-assembled monolayers of (3-mercaptopropyl) trimethoxysilane. Langmuir, 23(8), 4651-4661.
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  PMID: 17346068;Abstract: Investigation of the underpotential deposition (UPD) of three metals-Tl, Pb, and Cd-on Ag surfaces modified with self-assembled monolayers (SAMs) of (3-mercaptopropyl)trimethoxysilane (3MPT) is reported. On the basis of the observation of negative potential shifts for their UPD processes, Tl and Pb undergo UPD directly on the underlying Ag surface by insertion between the Ag-S bond. This process is proposed to occur by penetration of the 3MPT monolayer by hydrated metal ions through spaces in six-membered siloxane rings that form at the terminus of the 3MPT layer after hydrolysis and condensation. In contrast, Cd does not undergo similarly facile UPD at 3MPTmodified Ag electrodes due to a hydrated ion size too large to fit through these openings. The voltammetric evidence that suggests that the hydrated metal cation size, as described by the Stokes diameter, is the primary determinant of Ag electrode accessibility for UPD through the cross-linked 3MPT layer is further supported by molecular mechanics energy minimization computations of six-membered siloxane rings on each of the three low-index faces of Ag. Finally, the 3MPT monolayer is shown to be exceptionally stable to repeated UPD/stripping cycles of Tl and Pb in contrast to SAMs of similar thickness formed from normal alkanethiols. © 2007 American Chemical Society.
• Zangmeister, C. D., & Pemberton, J. E. (2007). Phase transition between two anhydrous modifications of NaHSO₄ mediated by heat and water. Journal of Solid State Chemistry, 180(6), 1826-1831.
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  Abstract: The phase transition between the two anhydrous modifications of NaHSO4 (α and β) was studied using Raman spectroscopy and differential scanning calorimetry. These measurements indicate that β-NaHSO4 is a metastable phase and readily undergoes phase transition to thermodynamically stable α-NaHSO4 with an exothermic enthalpy change of 3.5 kJ/mol. Both thermal (temperatures >434 K) and chemical (exposure to H2O) pathways were identified for this transition. The transition is irreversible, and α-NaHSO4 is an intermediate phase between β-NaHSO4 and NaHSO4·H2O. The possible mechanism of the phase transition is discussed. © 2007 Elsevier Inc. All rights reserved.
• Lebrón-Paler, A., Pemberton, J. E., Becker, B. A., Otto, W. H., Larive, C. K., & Maier, R. M. (2006). Determination of the acid dissociation constant of the biosurfactant monorhamnolipid in aqueous solution by potentiometric and spectroscopic methods. Analytical Chemistry, 78(22), 7649-7658.
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  PMID: 17105155;Abstract: The acid dissociation constant in water for a monorhamnolipid mixture extracted from Pseudomonas aeruginosa ATCC 9027 has been determined using potentiometry and two spectroscopic approaches at concentrations below and above the critical micelle concentration (cmc). Potentiometric titrations resulted in pKa values ranging from 4.28 ± 0.16 to 5.50 ± 0.06 depending on concentration. 1H NMR spectrochemical titrations at concentrations below the cmc revealed a pKa value of 4.39 ± 0.06. ATR-FT-IR spectrochemical titrations on solutions well above the cmc gave a pKa value of 4.84 ± 0.05. The value of 4.28 for the free rhamnolipid molecule for concentrations below the cmc differs markedly from that reported previously. However, the pKa of 5.50 for surface-adsorbed and solution aggregates correlates closely to that previously reported. Differences in these pKa values are rationalized in terms of the pH- and concentration-dependent aggregation behavior of rhamnolipids in aqueous solution. © 2006 American Chemical Society.
• Liao, Z., Orendorff, C. J., & Pemberton, J. E. (2006). Effects of Pressurized Solvent Environments on the Alkyl Chain Order of Octadecylsilane Stationary Phases by Raman Spectroscopy. Chromatographia, 65, 1-8.
• Liao, Z., Orendorff, C. J., Sander, L. C., & Pemberton, J. E. (2006). Structure-function relationships in high-density docosylsilane bonded stationary phases by Raman spectroscopy and comparison to octadecylsilane bonded stationary phases. Analytical Chemistry, 78(16), 5813-5822.
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  PMID: 16906728;Abstract: Raman spectroscopy is used to investigate the effects of temperature, surface coverage, polymerization method (surface or solution polymerized), and nature of the alkylsilane precursor on alkyl chain conformational order in a series of high-density docosylsilane (C22) stationary phases at surface coverages ranging from 3.61 to 6.97 μmol/m2. The results of this study contribute to an enhanced understanding of the shape-selective retention characteristics of these phases at a molecular level. Conformational order is evaluated using the intensity ratio of the antisymmetric and symmetric v(CH2) modes as well as the frequency at which these modes are observed. Alkyl chain order is shown to be dependent on surface coverage, alkyl chain length, and polymerization method. In general, alkyl chain order increases with surface coverage. Temperature-induced changes are observed between 250 and 350 K for the three phases with surface coverages between 3.61 and 4.89 μmol/m2. These changes occur over a broad range of temperatures characteristic of two-dimensional systems, but in general adhere to the behavior predicted for a simple first-order transition. This change is not believed to be an abrupt cooperative disassociation characteristic of a phase transition in a bulk phase, but instead is thought to involve significant changes in conformational order in segments of the surface-tethered molecules, mostly those segments at the outer edge of the alkylsilane. In contrast to the changes observed in coverages below 5 μmol/m2, a first-order change is not observed for the stationary phase with coverage of 6.97 μmol/m2. A molecular picture of the temperature-induced disorder is proposed with disorder originating at the distal carbon and propagating only a short distance toward the proximal carbon. A comparison is made between these C22 stationary phases and similar high-density octadecylsilane (C18) bonded phases. © 2006 American Chemical Society.
• Pasilis, S., Somogyi, Á., Herrmann, K., & Pemberton, J. E. (2006). Ions generated from uranyl nitrate solutions by electrospray ionization (ESI) and detected with Fourier transform ion-cyclotron resonance (FT-ICR) mass spectrometry. Journal of the American Society for Mass Spectrometry, 17(2), 230-240.
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  PMID: 16418004;Abstract: Electrospray ionization (ESI) of uranyl nitrate solutions generates a wide variety of positively and negatively charged ions, including complex adducts of uranyl ions with methoxy, hydroxy, and nitrate ligands. In the positive ion mode, ions detected by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry are sensitive to instrumental tuning parameters such as quadrupole operating frequency and trapping time. Positive ions correspond to oligomeric uranyl nitrate species that can be characterized as having a general formula of [(UO2)n(A)m(CH3OH)s] + or [(UO2)n(O)(A)m(CH 3OH)s]+ with n = 1-4, m = 1-7, s = 0 or 1, and A = OH, NO3, CH3O or a combination of these, although the formation of NO3-containing species is preferred. In the negative ion mode, complexes of the form [(UO2)(NO3)m] - (m = 1-3) are detected, although the formation of the oxo-containing ions [(UO2)(O)n(NO3) m]- (n = 1-2, m = 1-2) and the hydroxy-containing ions [(UO2)(OH)n(NO3)m]- (n = 1-2, m = 0-1) are also observed. The extent of coordinative unsaturation of both positive and negative ions can be determined by ligand association/exchange and H/D exchange experiments using D2O and CD3OD as neutral reaction partners in the gas-phase. Positive ions are of varying stability and reactivity and may fragment extensively upon collision with D2O, CD3OD and N2 in sustained off-resonance irradiation/collision-induced dissociation (SORI-CID) experiments. Electron-transfer reactions, presumably occurring during electrospray ionization but also in SORI-CID, can result in reduction of U(VI) to U(V) and perhaps even U(IV). © 2006 American Society for Mass Spectrometry.
• Pemberton, J., Liao, Z., & Pemberton, J. E. (2006). Raman spectral conformational order indicators in perdeuterated alkyl chain systems. The journal of physical chemistry. A, 110(51).
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  Conformational order indicators for perdeuterated alkyl chain systems are identified in the Raman spectra of nonadecane-d40, polyethylene-d4, and stearic acid-d35. Six spectral indicators are identified: I[nu(a)(CD2)2196]/I[nu(a)(CD2)2172], I[nu(C-C)G]/I[nu(C-C)T], I[nu(s)(CD3)]/I[nu(a)(CD2)2172], I[nu(s)(CD2)]/I[nu(a)(CD2)2172], and the full width at half-maximum (fwhm) and frequency of the nu(s)(CD2) mode. Among these indicators, the ratio of I[nu(a)(CD2)2196]/I[nu(a)(CD2)2172] is considered a primary indicator of conformational order, since it responds to alkyl chain conformational changes in a manner similar to the I[nu(a)(CH2)]/I[nu(s)(CH2)] primary indicator for hydrogenated systems. Other indicators are correlated to this primary indicator to derive a better understanding of the effect of structural attributes on conformational order in perdeuterated alkyl chain systems. These Raman spectral order indicators are applicable to any perdeuterated alkyl-containing system including lipids, biological membranes, alkylsilane-based chromatographic stationary phases, and self-assembled monolayers.
• Pemberton, J., Liao, Z., Orendorff, C. J., Sander, L. C., & Pemberton, J. E. (2006). Structure-function relationships in high-density docosylsilane bonded stationary phases by Raman spectroscopy and comparison to octadecylsilane bonded stationary phases. Analytical chemistry, 78(16).
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  Raman spectroscopy is used to investigate the effects of temperature, surface coverage, polymerization method (surface or solution polymerized), and nature of the alkylsilane precursor on alkyl chain conformational order in a series of high-density docosylsilane (C22) stationary phases at surface coverages ranging from 3.61 to 6.97 mumol/m(2). The results of this study contribute to an enhanced understanding of the shape-selective retention characteristics of these phases at a molecular level. Conformational order is evaluated using the intensity ratio of the antisymmetric and symmetric nu(CH2) modes as well as the frequency at which these modes are observed. Alkyl chain order is shown to be dependent on surface coverage, alkyl chain length, and polymerization method. In general, alkyl chain order increases with surface coverage. Temperature-induced changes are observed between 250 and 350 K for the three phases with surface coverages between 3.61 and 4.89 mumol/m(2). These changes occur over a broad range of temperatures characteristic of two-dimensional systems, but in general adhere to the behavior predicted for a simple first-order transition. This change is not believed to be an abrupt cooperative disassociation characteristic of a phase transition in a bulk phase, but instead is thought to involve significant changes in conformational order in segments of the surface-tethered molecules, mostly those segments at the outer edge of the alkylsilane. In contrast to the changes observed in coverages below 5 mumol/m(2), a first-order change is not observed for the stationary phase with coverage of 6.97 mumol/m(2). A molecular picture of the temperature-induced disorder is proposed with disorder originating at the distal carbon and propagating only a short distance toward the proximal carbon. A comparison is made between these C22 stationary phases and similar high-density octadecylsilane (C18) bonded phases.
• Pemberton, J., Pasilis, S., Somogyi, A., Herrmann, K., & Pemberton, J. E. (2006). Ions generated from uranyl nitrate solutions by electrospray ionization (ESI) and detected with Fourier transform ion-cyclotron resonance (FT-ICR) mass spectrometry. Journal of the American Society for Mass Spectrometry, 17(2).
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  Electrospray ionization (ESI) of uranyl nitrate solutions generates a wide variety of positively and negatively charged ions, including complex adducts of uranyl ions with methoxy, hydroxy, and nitrate ligands. In the positive ion mode, ions detected by Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry are sensitive to instrumental tuning parameters such as quadrupole operating frequency and trapping time. Positive ions correspond to oligomeric uranyl nitrate species that can be characterized as having a general formula of [(UO(2))(n)(A)(m)(CH(3)OH)(s)](+) or [(UO(2))(n)(O)(A)(m)(CH(3)OH)(s)](+) with n = 1-4, m = 1-7, s = 0 or 1, and A = OH, NO(3), CH(3)O or a combination of these, although the formation of NO(3)-containing species is preferred. In the negative ion mode, complexes of the form [(UO(2))(NO(3))(m)](-) (m = 1-3) are detected, although the formation of the oxo-containing ions [(UO(2))(O)(n)(NO(3))(m)](-) (n = 1-2, m = 1-2) and the hydroxy-containing ions [(UO(2))(OH)(n)(NO(3))(m)](-) (n = 1-2, m = 0-1) are also observed. The extent of coordinative unsaturation of both positive and negative ions can be determined by ligand association/exchange and H/D exchange experiments using D(2)O and CD(3)OD as neutral reaction partners in the gas-phase. Positive ions are of varying stability and reactivity and may fragment extensively upon collision with D(2)O, CD(3)OD and N(2) in sustained off-resonance irradiation/collision-induced dissociation (SORI-CID) experiments. Electron-transfer reactions, presumably occurring during electrospray ionization but also in SORI-CID, can result in reduction of U(VI) to U(V) and perhaps even U(IV).
• Zhaohui, L., & Pemberton, J. E. (2006). Raman spectral conformational order indicators in perdeuterated alkyl chain systems. Journal of Physical Chemistry A, 110(51), 13744-13753.
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  PMID: 17181330;Abstract: Conformational order indicators for perdeuterated alkyl chain systems are identified in the Raman spectra of nonadecane-d40, polyethylene-d4, and stearic acid-d35. Six spectral indicators are identified: I[va(CD2)2196]/ I[va(CD2)2172], I[v(C-C)G]/I[v(C-C) T], I[vs(CD3)]/I[va(CD 2)2172], I[vs(CD2)]/I[v a(CD2)2172], and the full width at half-maximum (fwhm) and frequency of the vs(CD2) mode. Among these indicators, the ratio of I[va-(CD2)2196]/ I[va(CD2)2172] is considered a primary indicator of conformational order, since it responds to alkyl chain conformational changes in a manner similar to the I[va(CH 2)]/I[vs(CH2)] primary indicator for hydrogenated systems. Other indicators are correlated to this primary indicator to derive a better understanding of the effect of structural attributes on conformational order in perdeuterated alkyl chain systems. These Raman spectral order indicators are applicable to any perdeuterated alkyl-containing system including lipids, biological membranes, alkylsilane-based chromatographic stationary phases, and self-assembled monolayers. © 2006 American Chemical Society.
• Liao, Z., & Pemberton, J. E. (2005). In situ adsorption studies of 1-octanol on silica surfaces by ATR-FTIR. ACS National Meeting Book of Abstracts, 230.
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  Abstract: The adsorption of molecules from liquid solution onto silica surfaces is important for many areas of science and technology including LC, coatings, sol-gel sensors, and chemical modification of oxide surfaces. The in situ adsorption of 1-octanol on thin silica sol-gel films in contact with dilute cyclohexane solutions of 1-octanol was studied using Attenuated total reflection-FTIR. The silica sol-gel film was deposited onto a ZnSe internal reflection element by dip-coating with the resulting silica sol film thickness controlled to be < 1 pm. The entire adsorption isotherm for 1-octanol on silica was studied using cyclohexane solutions ranging in concentration from 4.5 × 10-4 to 1.9 × 10-1 M in 1-octanol. The adsorption isotherm for this system was presented and relevant adsorption constants were determined from the isotherm. This is an abstract of a paper presented at the 230th ACS National Meeting (Washington, DC 8/28/2005-9/1/2005).
• Orendorff, C. J., & Pemberton, J. E. (2005). Alkylsilane-based stationary phases via a displaceable surface template approach: Synthesis, characterization, and chromatographic performance. Analytical Chemistry, 77(18), 6069-6077.
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  PMID: 16159143;Abstract: A method is presented for the preparation of silica-based alkylsilane stationary phases using octanol as a displaceable surface template to control the rate of alkylsilane condensation with the silica surface, and thereby, the resulting alkylsilane surface coverage. This method improves upon conventional preparation schemes by allowing alkylsilane stationary phases of systematically varying surface coverage to be prepared from a single reaction mixture and a single precursor molecule without rigorous control of water content of the solution or of the silica. Octadecylsilane stationary phases ranging in surface coverage from ∼3.5 to 6.0 μmol/m2 were synthesized using one set of experimental conditions with variation of only the octadecylsilane/ octanol ratio. The conformational order of the octadecylsilane alkyl chains was assessed using Raman spectroscopy and was found to increase with increasing surface coverage in a manner similar to stationary phases prepared by conventional routes. As chromatographic stationary phases in microbore columns for the reversed-phase separation of monosubstituted aromatic compounds, the performance of these materials is comparable to or better than that of commercially available octadecylsilane stationary phases under identical chromatographic conditions. Furthermore, the high-density stationary phases (> 3.5 μmol/m2) prepared by this route exhibit geometric shape selectivity comparable to or better than that reported earlier for high-density octadecylsilane stationary phases prepared using conventional methods. © 2005 American Chemical Society.
• Orendorff, C. J., & Pemberton, J. E. (2005). Raman spectroscopic study of the conformational order of octadecylsilane stationary phases: Effects of electrolyte and pH. Analytical and Bioanalytical Chemistry, 382(3), 691-697.
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  PMID: 15770468;Abstract: This study investigates effects of the electrolyte, of acidic and basic compounds, and of pH on the rotational and conformational order of octadecylsilane stationary phases with surface coverages of 3.09 and 6.45 μmol/m2. Both phases exhibit an increase in alkyl chain rotational and conformational order in 5-200 mM aqueous electrolyte solutions relative to water. These stationary phases are effectively "salted-out" of aqueous electrolyte solutions, thereby causing alkyl chain intermolecular interactions to increase with a concomitant increase in alkyl chain order. Although the presence of acidic and basic compounds generally has no effect on the conformational order of either stationary phase as a function of pH, the higher coverage stationary phase does exhibit pH-dependent changes in aqueous solutions of benzoic acid. At pH values below the pK a of benzoic acid, the conformational order of this stationary phase is unchanged relative to that observed in the same pH solution in the absence of benzoic acid. In light of independent evidence that such monosubstituted aromatics interact with the octadecylsilane stationary phase under these conditions, the absence of a measurable effect on alkyl chain order for these conditions is attributed to benzoic acid self-association at the stationary phase-mobile phase interface. In contrast, at pH values above the pK a of benzoic acid, slight disordering of the alkyl chains is observed and is attributed to repulsive interactions between retained benzoate anions. © Springer-Verlag 2005.
• Pemberton, J., Orendorff, C. J., & Pemberton, J. E. (2005). Alkylsilane-based stationary phases via a displaceable surface template approach: synthesis, characterization, and chromatographic performance. Analytical chemistry, 77(18).
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  A method is presented for the preparation of silica-based alkylsilane stationary phases using octanol as a displaceable surface template to control the rate of alkylsilane condensation with the silica surface, and thereby, the resulting alkylsilane surface coverage. This method improves upon conventional preparation schemes by allowing alkylsilane stationary phases of systematically varying surface coverage to be prepared from a single reaction mixture and a single precursor molecule without rigorous control of water content of the solution or of the silica. Octadecylsilane stationary phases ranging in surface coverage from approximately 3.5 to 6.0 micromol/m(2) were synthesized using one set of experimental conditions with variation of only the octadecylsilane/octanol ratio. The conformational order of the octadecylsilane alkyl chains was assessed using Raman spectroscopy and was found to increase with increasing surface coverage in a manner similar to stationary phases prepared by conventional routes. As chromatographic stationary phases in microbore columns for the reversed-phase separation of monosubstituted aromatic compounds, the performance of these materials is comparable to or better than that of commercially available octadecylsilane stationary phases under identical chromatographic conditions. Furthermore, the high-density stationary phases (>3.5 micromol/m(2)) prepared by this route exhibit geometric shape selectivity comparable to or better than that reported earlier for high-density octadecylsilane stationary phases prepared using conventional methods.
• Pemberton, J., Orendorff, C. J., & Pemberton, J. E. (2005). Raman spectroscopic study of the conformational order of octadecylsilane stationary phases: effects of electrolyte and pH. Analytical and bioanalytical chemistry, 382(3).
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  This study investigates effects of the electrolyte, of acidic and basic compounds, and of pH on the rotational and conformational order of octadecylsilane stationary phases with surface coverages of 3.09 and 6.45 micromol/m(2). Both phases exhibit an increase in alkyl chain rotational and conformational order in 5-200 mM aqueous electrolyte solutions relative to water. These stationary phases are effectively "salted-out" of aqueous electrolyte solutions, thereby causing alkyl chain intermolecular interactions to increase with a concomitant increase in alkyl chain order. Although the presence of acidic and basic compounds generally has no effect on the conformational order of either stationary phase as a function of pH, the higher coverage stationary phase does exhibit pH-dependent changes in aqueous solutions of benzoic acid. At pH values below the pK(a) of benzoic acid, the conformational order of this stationary phase is unchanged relative to that observed in the same pH solution in the absence of benzoic acid. In light of independent evidence that such monosubstituted aromatics interact with the octadecylsilane stationary phase under these conditions, the absence of a measurable effect on alkyl chain order for these conditions is attributed to benzoic acid self-association at the stationary phase-mobile phase interface. In contrast, at pH values above the pK(a) of benzoic acid, slight disordering of the alkyl chains is observed and is attributed to repulsive interactions between retained benzoate anions.
• Zangmeister, C. D., & Pemberton, J. E. (2004). Erratum: Raman spectroscopy of the reaction of sodium chloride with nitric acid: Sodium nitrate growth and effect of water exposure (J. Phys. Chem. A (2001) 105 (3788-3795)). Journal of Physical Chemistry A, 108(1), 236-.
• Hawkridge, A. M., & Pemberton, J. E. (2003). Model aluminum-poly(p-phenylenevinylene) interfaces studied by surface Raman spectroscopy. Journal of the American Chemical Society, 125(3), 624-625.
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  PMID: 12526649;Abstract: Polymeric organic light-emitting diodes (OLEDs) have emerged as inexpensive and versatile alternatives to traditional inorganic-based display technologies. Further advances in this field depend on extending device lifetimes and improving electroluminescence efficiencies, both of which are strongly coupled to the integrity of the electrode/organic contacts. Therefore, the deposition of low-work function metals on organic materials has been extensively studied by X-ray photoelectron spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS), and near-edge X-ray adsorption fine structure (NEXAFS) to ascertain information about the chemical and electronic states within the interfacial region. However, to date, the only molecular structural information about metal-organic species formed in these regions has come from fits of theoretical models to existing XPS and UPS data. Very little direct structural information exists about the potential multitude of metal-organic species formed during cathode deposition. We report the use of surface Raman spectroscopy to study the interactions between aluminum and trans-stilbene, a model for poly(p-phenylenevinylene) (PPV). The Raman spectral data suggest preferential formation of covalent Al-C bonds at the vinylene carbons as opposed to the phenyl carbons of PPV. Copyright © 2003 American Chemical Society.
• Orendorff, C. J., Ducey Jr., M. W., Pemberton, J. E., & Sander, L. C. (2003). Structure-function relationships in high-density octadecylsilane stationary phases by Raman spectroscopy. 3. Effects of self-associating solvents. Analytical Chemistry, 75(14), 3360-3368.
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  PMID: 14570185;Abstract: Raman spectroscopy is used to examine the subtle effects of polar, hydrogen-bonding solvents; temperature; and the surface grafting method (surface- or solution-polymerized) on alkyl chain rotational and conformational order in a series of high-density octadecylsilane stationary phases ranging in surface coverage from 3.09 to 6.45 μmol/m2. Rotational and conformational order is assessed using the intensity ratio of the antisymmetric to symmetric v(CH2) modes as well as the frequencies at which these Raman bands are observed. Alkyl rotational and conformational order decreases with decreasing surface coverage in these polar solvents, consistent with the behavior of these materials in air. For homogeneously distributed, high surface coverage materials, these polar solvents induce rotational ordering that is proposed to be due to the self-association of these solvents through hydrogen bonding or other dipole interactions at the alkylsilane-solvent interface. From these observations, molecular pictures of these solvent-stationary-phase interfaces are proposed in which solvent interaction with the stationary phase occurs primarily at the distal methyl group of the alkyl chains.
• Orendorff, C. J., Ducey Jr., M. W., Pemberton, J. E., & Sander, L. C. (2003). Structure-function relationships in high-density octadecylsilane stationary phases by Raman spectroscopy. 4. Effects of neutral and basic aromatic compounds. Analytical Chemistry, 75(14), 3369-3375.
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  PMID: 14570186;Abstract: The effects of aromatic compounds (toluene, benzene, p-xylene, anisole, aniline, and pyridine), temperature, and surface grafting method (surface- or solution-polymerized) on alkyl chain rotational and conformational order in a series of high-density octadecylsilane stationary phases ranging in surface coverage from 3.09 to 6.45 μmol/m2 are examined by Raman spectroscopy. Rotational and conformational order are assessed using the intensity ratio of the antisymmetric to symmetric v(CH2) modes as well as the frequency at which the symmetric v(CH2) band is observed. Alkyl rotational and conformational order decrease with decreasing surface coverage in these aromatic compounds, which is consistent with the behavior of these materials in air and in other solvents. In addition, order of the alkyl chains is dependent on solvent hydrophobicity, hydrogen-bonding ability, and basicity. The most hydrophobic compounds impart disorder to the stationary phase; the hydrogen-bonding aromatics increase the rotational order of homogeneously distributed, high-surface-coverage materials; and basic aromatic compounds increase the conformational order of high- and low-coverage materials as the basic compounds undergo silanophilic interactions with exposed surface silanols. From these observations, molecular pictures of the chromatographic interface that display interactions between the alkyl chains and these aromatic compounds are proposed.
• Pasilis, S. P., & Pemberton, J. E. (2003). Speciation and Coordination Chemistry of Uranyl(VI)-Citrate Complexes in Aqueous Solution. Inorganic Chemistry, 42(21), 6793-6800.
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  PMID: 14552631;Abstract: The pH dependence of uranyl(VI) complexation by citric acid was investigated using Raman and attenuated total reflection FTIR spectroscopies and electrospray ionization mass spectrometry. pH-dependent changes in the νs(UO2) envelope indicate that three major UO 22+-citrate complexes with progressively increasing U=O bond lengths are present over a range of pH from 2.0 to 9.5. The first species, which is the predominant form of uranyl(VI) from pH 3.0 to 5.0, contains two UO22+ groups in spectroscopically equivalent coordination environments and corresponds to the [(UO2)2Cit 2]2- complex known to exist in this pH range. At pH values >6.5, [(UO2)2Cit2]2- undergoes ah an interconversion to form [(UO2)3Cit 3]3- and (UO2)3Cit2. ESI-MS studies on solutions of varying uranyl(VI)/citrate ratios, pH, and solution counteranion were successfully used to confirm complex stoichiometries. Uranyl and citrate concentrations investigated ranged from 0.50 to 50 mM.
• Pemberton, J., Hawkridge, A. M., & Pemberton, J. E. (2003). Model aluminum-poly(p-phenylenevinylene) interfaces studied by surface raman spectroscopy. Journal of the American Chemical Society, 125(3).
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  Polymeric organic light-emitting diodes (OLEDs) have emerged as inexpensive and versatile alternatives to traditional inorganic-based display technologies. Further advances in this field depend on extending device lifetimes and improving electroluminescence efficiencies, both of which are strongly coupled to the integrity of the electrode/organic contacts. Therefore, the deposition of low-work function metals on organic materials has been extensively studied by X-ray photoelectron spectroscopy (XPS), ultraviolet photoemission spectroscopy (UPS), and near-edge X-ray adsorption fine structure (NEXAFS) to ascertain information about the chemical and electronic states within the interfacial region. However, to date, the only molecular structural information about metal-organic species formed in these regions has come from fits of theoretical models to existing XPS and UPS data. Very little direct structural information exists about the potential multitude of metal-organic species formed during cathode deposition. We report the use of surface Raman spectroscopy to study the interactions between aluminum and trans-stilbene, a model for poly(p-phenylenevinylene) (PPV). The Raman spectral data suggest preferential formation of covalent Al-C bonds at the vinylene carbons as opposed to the phenyl carbons of PPV.
• Pemberton, J., Pasilis, S. P., & Pemberton, J. E. (2003). Speciation and coordination chemistry of uranyl(VI)-citrate complexes in aqueous solution. Inorganic chemistry, 42(21).
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  The pH dependence of uranyl(VI) complexation by citric acid was investigated using Raman and attenuated total reflection FTIR spectroscopies and electrospray ionization mass spectrometry. pH-dependent changes in the nu(s)(UO(2)) envelope indicate that three major UO(2)(2+)-citrate complexes with progressively increasing U=O bond lengths are present over a range of pH from 2.0 to 9.5. The first species, which is the predominant form of uranyl(VI) from pH 3.0 to 5.0, contains two UO(2)(2+) groups in spectroscopically equivalent coordination environments and corresponds to the [(UO(2))(2)Cit(2)](2)(-) complex known to exist in this pH range. At pH values >6.5, [(UO(2))(2)Cit(2)](2)(-) undergoes an interconversion to form [(UO(2))(3)Cit(3)](3)(-) and (UO(2))(3)Cit(2). ESI-MS studies on solutions of varying uranyl(VI)/citrate ratios, pH, and solution counteranion were successfully used to confirm complex stoichiometries. Uranyl and citrate concentrations investigated ranged from 0.50 to 50 mM.
• Tiani, D. J., & Pemberton, J. E. (2003). Emersion of 11-mercapto-1-undecanol-modified Ag substrates from aqueous and nonaqueous solvents: The effect of emersion velocity on emersed solvent layer thickness. Langmuir, 19(16), 6422-6429.
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  Abstract: The formation and stabilization of the emersed interface is dependent on the interplay of various hydrodynamic (viscosity, emersion velocity) and intermolecular forces (hydrogen bonding, dipole-dipole). In an effort to better define the role of these forces, manual-null ellipsometry has been used to investigate the effect of emersion velocity on the emersed layer thickness of water, methanol, acetonitrile, chloroform, 1-butanol, and 1-pentanol at self-assembled monolayers of 11-mercapto-1-undecanol (11-MUD) on polycrystalline Ag substrates. Emersed solvent layer thicknesses decrease as emersion velocity increases for water, methanol, acetonitrile, and chloroform. In contrast, the emersed layer thicknesses of 1-butanol and 1-pentanol remain relatively constant as the emersion velocity increases over the range of velocities accessible (0.0055-0.037 cm/s). These data suggest that the effect of emersion velocity on the resulting emersed layer thickness depends on the chemical and physical characteristics of the solvent. A descriptive model has been developed to describe the emersion process in terms of the interplay between hydrodynamic and intermolecular forces. According to this model, a shear plane develops at some distance away from the solid surface when the hydrodynamic forces are great enough to overcome the intermolecular forces between the liquid layers that behave as a Newtonian fluid at the molecular level.
• Ducey Jr., M. W., Orendorff, C. J., Pemberton, J. E., & Sander, L. C. (2002). Structure-function relationships in high-density octadecylsilane stationary phases by Raman spectroscopy. 1. Effects of temperature, surface coverage, and preparation procedure. Analytical Chemistry, 74(21), 5576-5584.
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  PMID: 12433091;Abstract: Raman spectroscopy is used to examine the effects of temperature, surface coverage, nature of the alkylsilane precursor (octadecyltrichlorosilane, methyloctadecyldichlorosilane, or dimethyloctadecylchlorosilane), and surface grafting method (surface or solution polymerized) on alkyl chain conformational order in a series of high-density octadecylsilane stationary phases ranging in surface coverage from 3.09 to 6.45 μmol/m2. Conformational order is assessed using the intensity ratio of the antisymmetric and symmetric v(CH2) modes as well as the frequency at which these Raman bands are observed. Conformational order increases with surface coverage. Temperature-induced surface phase changes are observed between 258 and 343 K for this homologous series of stationary phases that are demonstrated to adhere to the Clapeyron equation for a simple first-order transition. Phase changes are discussed in terms of variation of the molar enthalpy, molar entropy, and molar volume of the stationary phase, all of which depend on surface coverage. For the limited range of systems investigated, a correlation between stationary-phase preparation (surface versus solution polymerized and nature of the silane precursor) and extent of alkyl chain order is not clearly observed. Instead, alkyl chain order is largely dependent on bonding density. A molecular picture of temperature-induced disorder in octadecylsilane stationary phases is proposed, with disorder originating at the distal carbon and propagating toward the proximal carbon.
• Ducey Jr., M. W., Orendorff, C. J., Pemberton, J. E., & Sander, L. C. (2002). Structure-function relationships in high-density octadecylsilane stationary phases by Raman spectroscopy. 2. Effect of common mobile-phase solvents. Analytical Chemistry, 74(21), 5585-5592.
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  PMID: 12433092;Abstract: Raman spectroscopy is used to examine the effects of solvent, temperature, and surface grafting method (surface or solution polymerized) on alkyl chain rotational and conformational order in a series of high-density octadecylsilane stationary phases ranging in surface coverage from 3.09 to 6.45 μmol/m2. Rotational and conformational order is assessed using the intensity ratio of the antisymmetric to symmetric v(CH2) modes as well as the frequency at which these Raman bands are observed. Solvents studied include perdeuterated hexane, toluene, chloroform, tetrahydrofuran, benzene, methanol, acetone, acetonitrile, and water. Stationary-phase order was investigated at temperatures between 258 and 323 K. Alkyl chain rotational and conformational order, and hence, solvation of the stationary phase, is dependent on solvent parameters (polarity, size, etc.), temperature, and stationary-phase properties (polymerization method and surface coverage). Information on stationary-phase conformational order allows solvent-stationary-phase interactions to be described in terms of a combination of adsorption and partitioning models for reversed-phase liquid chromatography. Finally, a distinct interplay between solvent-and temperature-induced ordering of these stationary phases is documented that is also a function of solvent and stationary-phase properties.
• Orendorff, C. J., Ducey Jr., M. W., & Pemberton, J. E. (2002). Quantitative correlation of Raman spectral indicators in determining conformational order in alkyl chains. Journal of Physical Chemistry A, 106(30), 6991-6998.
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  Abstract: The correlation of Raman spectral indicators for the determination of alkyl chain interactions and conformational order is presented. These investigations probe the conformational order of bulk octadecane and low molecular weight polyethylene as they undergo solid/liquid phase transitions. Spectral indicators are quantitatively correlated to the I[va(CH2)]/I[vs(CH2)], as this is the primary indicator of rotational and conformational order obtained empirically from Raman spectra. These indicators are interpreted in terms of alkane intramolecular motion, intermolecular interactions between alkyl chains, crystal structure of these solid materials, and the presence of methylene conformers. Results demonstrate that Raman spectroscopy is sensitive to very subtle changes in alkane chain structure and conformation. These results can be used to understand molecular interactions and structure-function relationships in alkane-based materials.
• Cai, M., & Pemberton, J. E. (2001). Vibrational spectroscopy of dimethylchlorooctadecylsilane covalently bonded to ultrathin silica films immobilized on Ag surfaces. Fresenius' Journal of Analytical Chemistry, 369(1), 328-334.
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  PMID: 11293712;Abstract: FTIR and Raman spectroscopies have been used to characterize the structure and conformational order of dimethylchlorooctadecylsilane (DOS) covalently bonded to ultrathin silica films supported on Ag substrates. Ultrathin silica films of ca. 30 Å thickness prepared from sol-gel methods are immobilized on Ag surfaces modified with a self-assembled monolayer of (3-mercaptopropyl)trimethoxysilane (3MPT). This layered structure provides a unique opportunity for acquiring complementary spectral data from both FTIR and Raman spectroscopies, which are useful in elucidating alkylsilane conformation pertaining to stationary phases for reversed-phase liquid chromatography (RPLC). Characterization of octadecyltrichlorosilane (OTS) layers on thin silica films of ca. 800 Å thickness on 3MPT-modified Ag surfaces has been reported previously. Differences between the ultrathin silica films used in this study and the thin silica filmsused in this previous study are considered. The results from both FTIR and Raman spectroscopy presented here suggest that bonded DOS alkyl chains are in a disordered, liquid-like state with close to monolayer surface coverage.
• Kambhampati, D. K., A., T., Robertson, J. W., Cai, M., Pemberton, J. E., & Knoll, W. (2001). Novel silicon dioxide sol-gel films for potential sensor applications: a surface plasmon resonance study. Langmuir, 17(4), 1169-1175.
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  Abstract: Stable silicon dioxide (silica, SiO2) films on noble metals were synthesized using a novel sol-gel technique. Surface plasmon resonance (SPR) spectroscopy was used to compare the stability of silica films generated by this sol-gel technique with those deposited by using thermal evaporation, in the presence of PBS buffer. These films were later chemically functionalized with various reactive groups as a test for their versatility and usefulness in sensoric applications. A surface grating enclosed in a high-pressure and elevated temperature cell was used in the investigation of polymer brushes while SPR coupled with fluorescence detection schemes was used in the Kretschmann prism configuration to monitor DNA hybridization interactions.
• Pemberton, J. E., Mankit, H. o., Orendorff, C. J., & Ducey, M. W. (2001). Raman spectroscopy of octadecylsilane stationary phase conformational order: Effect of solvent. Journal of Chromatography A, 913(1-2), 243-252.
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  PMID: 11355819;Abstract: The effect of solvent on the conformation of alkyl chains of two octadecysilane-based stationary phases is probed using Raman spectroscopy. Spectral data indicate that the alkyl chains of commercially available polymeric and monomeric solid-phase extraction stationary phases are disordered to a varying extent by solvents of different polarity. For the polymeric octadecylsilane stationary phase, the polar solvents water, acetonitrile, methanol, acetone and isopropanol have little impact on the conformational order of the octadecylsilane bonded phase relative to air. However, the alkyl portion of this stationary phase is substantially disordered in the low-polarity solvents tetrahydrofuran, chloroform, benzene, toluene and hexane. The monomeric octadecylsilane stationary phase is less susceptible to disordering by solvents, although more disorder in the less polar solvents is also observed for this system. These results are interpreted in terms of the local surface bonding density and interchain spacing of these two stationary phases, and the ability of the solvent to penetrate the chains as a function of polarity. The results clearly demonstrate the ability of Raman spectroscopy to precisely indicate subtle changes in conformational order of alkylsilane stationary phases. © 2001 Elsevier Science B.V.
• Robertson, J. W., Cai, M., & Pemberton, J. E. (2001). Insulating ultrathin silica films formed by a room-temperature sol-gel process. Advanced Materials, 13(9), 662-667.
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  Abstract: Sol-gel ultrathin dielectric surfaces were derived without high-temperature annealing step. The surfaces exhibit good electronic properties, high resistivities and intrinsically low capacitances.
• Zangmeister, C. D., & Pemberton, J. E. (2001). Raman spectroscopy of the reaction of sodium chloride with nitric acid: Sodium nitrate growth and effect of water exposure. Journal of Physical Chemistry A, 105(15), 3788-3795.
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  Abstract: The reaction of powdered NaCl with HNO3 was studied using Raman spectroscopy. NaNO3 growth was monitored as a function of HNO3 exposure in a flow cell. Mode-specific changes in the NO3- vibrational mode intensities with HNO3 exposure suggest a rearrangement of the NaNU3 film with coverage. In the absence of H2O, intensities of NaNO3 bands increase with HNOj exposure until a capping layer of NaNO3 forms. The capping layer prevents subsequent HNO3 from reacting with the underlying NaCl. H2O exposure of NaNO3-capped NaCl results in hydration of the surface to form an aqueous solution containing NaNO3 and NaCl. Further exposure results in the formation of a thicker surface-adsorbed H2O layer that is consistent with an aqueous NaNO3 and NaCl solution. Upon exposure of hydrated NaCl to HNO3, molecular HNO3 and solid-state NaNO3 are observed in the thin H2O film. © 2001 American Chemical Society.
• Zangmeister, C. D., Jessica, A. T., & Pemberton, J. E. (2001). Segregation of NaBr in NaBr/NaCl crystals grown from aqueous solutions: Implications for sea salt surface chemistry. Geophysical Research Letters, 28(6), 995-998.
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  Abstract: Surface segregation of NaBr in mixed NaBr/NaCl crystals precipitated from aqueous solutions containing Br is investigated. Crystals were grown from solutions of a wide range of Br:Cl values and studied using x-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy-dispersive x-ray flourescence (EDX), and atomic force microscopy (AFM). Results indicates that NaBr surface-segregates to cover 4-5% of the surface at the Br:Cl value found in Sea water (1:660). The surface NaBr:NaCl values are ~ 35 times higher those of the bulk crystals. The surface NaBr forms domains of average size 635 nm x 635 nm x 53 nm. Large areas of the surface contain NaCl with no detectable NaBr. Complete surface segregation of all Br found in sea salt particles is likely to occur, thereby making a greater amount of Br available for surface reactions with gas-phase constituents than would be predicted based on bulk composition.
• Cai, M., Mankit, H. o., & Pemberton, J. E. (2000). Surface vibrational spectroscopy of alkylsilane layers covalently bonded to monolayers of (3-mercaptopropyl)trimethoxysilane on Ag substrates. Langmuir, 16(7), 3446-3453.
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  Abstract: Fourier transform IR and Raman spectroscopy have been used to characterize the structure and conformational order of octadecyltrichlorosilane (OTS) and dimethylchlorooctadecylsilane (DOS) covalently bonded to Ag surfaces modified with a hydrolyzed and condensed self-assembled monolayer of (3-mercaptopropyl)trimethoxysilane (3MPT). This 3MPT layer is used as a model silica surface with a very low surface silanol density and, hence, much less surface-confined water than normal silica surfaces. OTS bonds to this surface at the silanol sites in heterogeneous polymeric islands possessing both highly crystalline and disordered domains. DOS bonds in submonolayer coverages with its alkyl chains in a disordered state. The results from both FTIR and Raman spectroscopies confirm the critical role of surface water in forming highly crystalline assemblies of cross-linked alkylsilanes.
• Cai, M., Mowery, M. D., Pemberton, J. E., & Evans, C. E. (2000). Dual-wavelength resonance Raman spectroscopy of polydiacetylene monolayers on Au surfaces. Applied Spectroscopy, 54(1), 31-38.
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  Abstract: In this paper, resonance Raman spectroscopy with dual-wavelength laser excitation is applied to study the chromatic phase properties of self-assembled diacetylene monolayers on atomically flat Au surfaces. Laser excitation at 632.8 nm is utilized to exclusively monitor the longer conjugation length blue-phase polydiacetylene (PDA) backbone structure, while laser excitation at 514.5 nm is applied to probe the shorter conjugation length red phase. This experimental design allows in situ measurement of the photophysics and chemistry of the polymerization process within a single molecular layer. These studies demonstrate the presence of multiple chromatic species of PDAs within the same monolayer structure. Similar to observations for analogous thin film and multilayer assemblies, systematic conversion from the higher conjugation length blue form of the polymer to the shorter conjugation length red form is observed upon extended UV irradiation. Moreover, a very large Raman dispersion of 130 cm-1/eV is measured, demonstrating the highly conjugated nature of these monolayer polymers. Finally, backbone planarity and strain during the polymerization process are assessed by using the correlation of double- and triple-bond stretching frequencies.
• Gailer, J., George, G. N., Pickering, I. J., Prince, R. C., Ringwald, S. C., Pemberton, J. E., Glass, R. S., Younis, H. S., DeYoung, D. W., & Aposhian, H. V. (2000). A Metabolic Link Between Arsenite and Selenite: The Seleno-bis(S-glutathionyl) Arsinium Ion. Journal of the American Chemical Society, 122, 4637-4639.
• Pemberton, J. E. (2000). Challenges for the analytical chemistry curriculum. Analytical Chemistry, 72(5), 173A.
• Pemberton, J. E., & Chamberlain, J. R. (2000). Raman spectroscopy of model membrane monolayers of dipalmitoylphosphatidic acid at the air-water interface using surface enhancement from buoyant thin silver films. Biopolymers - Biospectroscopy Section, 57(2), 103-116.
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  PMID: 10766961;Abstract: A novel method for the acquisition of surface enhanced Raman (SER) spectra of model membranes of dipalmitoylphosphatidic acid (DPPA) in Langmuir layers at the air-water interface is reported. The approach is based on the electrochemical formation of a buoyant thin layer of coalesced silver colloids in the vicinity of the phosphatidic acid head groups at the interface. This Ag layer is an excellent platform for SER scattering, which shows the spectral features from all parts of the molecule and water between the Ag surface and the DPPA layer. The observation of the spectral response from the phosphatidic acid head groups is of particular significance, allowing insight into their chemical state and orientation at the air-water interface. (C) 2000 John Wiley and Sons, Inc.
• Ringwald, S. C., & Pemberton, J. E. (2000). Adsorption interactions of aromatics and heteroaromatics with hydrated and dehydrated silica surfaces by raman and FTIR spectroscopies. Environmental Science and Technology, 34(2), 259-265.
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  Abstract: Raman and FTIR spectroscopies are used to investigate the sorption mechanisms of benzene, toluene, and 2- and 4-picoline onto silica as models for volatile aromatic pollutant interactions with a soil constituent. Benzene and toluene vapor adsorption on silica occurs via weak π-system-hydrogen bonding with silanols on the silica surface. This weak interaction would likely result in low vadose zone retention, especially in wet conditions where water adsorption would successfully compete for surface sites. The vapor adsorption of 2- and 4-picoline (2- and 4-methylpyridine) is studied to model aza-arene environmental contaminants. These species adsorb to surface silanols by a more specific and stronger hydrogen-bonding mechanism involving the lone pair electrons on the N atom. The strength of these interactions is probably sufficient to result in their retention by dry or damp vadose zone soil, slowing their transport. This work illustrates the utility of these vibrational spectroscopic techniques in elucidating specific surface interactions of pollutants with mineral oxides and in helping to predict the fate of pollutants in the environment.
• Schoenfisch, M. H., Ovadia, M., & Pemberton, J. E. (2000). Covalent surface chemical modification of electrodes for cardiac pacing applications. Journal of Biomedical Materials Research, 51(2), 209-215.
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  PMID: 10825220;Abstract: We report the covalent surface modification of active-fixation pacemaker electrodes with butanethiol or dodecanethiol self-assembled monolayers (SAMs) using a platinum or gold metal-thiolate bond (i.e., changing the chemical identity of the exposed metal electrode from metal to organic) in such fashion that (a) the surface is organic in functionality with lipophilic physicochemical characteristics, (b) a possible degradation product is gold (I)-alkanethiolate with putative anti-inflammatory actions, and (c) current density/electric field strength is increased. Superior acute and chronic pacing performance with dodecanethiol-modified, gold-coated, platinum-iridium alloy pacemaker electrodes was observed with inferential evidence of reduced inflammation and scar. This approach may have applicability in other areas of bioelectrodes with practical applications in clinical cardiology, surgery, neuroscience, and subcutaneous sensors. (C) 2000 John wiley and Sons, Inc.
• Schoenfisch, M. H., Ross, A. M., & Pemberton, J. E. (2000). Electrochemical cleaning of surface-confined carbon contamination in self-assembled monolayers on polycrystalline Ag and Au. Langmuir, 16(6), 2907-2914.
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  Abstract: A protocol for electrochemical cleaning of carbon-contaminated alkanethiol SAMs at mechanically polished (MP) Ag surfaces is characterized by surface Raman spectroscopy and electrochemistry. Vibrational information in the v(C-S), v(C-C), v(C-H), and δ(C-H) regions is particularly useful in elucidating the degree of order and amount of contamination in propanethiol, dodecanethiol, and octadecanethiol monolayers before and after negative potential exposure in several aqueous electrolytes. Specifically, Raman spectra indicate that electrochemical cleaning of alkanethiol SAMs at potentials negative of the thiolate reduction removes carbonaceous species and greatly increases the film order near the sulfur headgroup.
• Taylor, C. E., Schoenfisch, M. H., & Pemberton, J. E. (2000). Sequestration of carbonaceous species within alkanethiol self-assembled monolayers on Ag by Raman spectroscopy. Langmuir, 16(6), 2902-2906.
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  Abstract: Raman spectra of hydrogenated CnSH (where, n=3-5,8,9,12, and 18) and C8D17SH SAMs at mechanically polished (MP) Ag indicate monolayer contamination by a small polyaromatic hydrocarbon (PAH). The contaminant source at the unmodified MP Ag surface is identified using Raman spectroscopy, and thus, the contaminant is believed to be placed at this surface during the mechanical polishing procedure. Notably, the PAH contaminant is not completely removed by either solvent dissolution or alkanethiol adsorption, suggesting that it is strongly bound, and more significantly, sequestered within the alkanethiol SAM. Controlled incorporation of pyrene into dodecanethiol SAMs demonstrates that doping of alkanethiol SAMs may be possible for certain systems.
• Zangmeister, C. D., & Pemberton, J. E. (2000). Raman spectroscopy and atomic force microscopy of the reaction of sulfuric acid with sodium chloride. Journal of the American Chemical Society, 122(49), 12289-12296.
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  Abstract: The reaction of NaCl with H2SO4 is investigated using Raman spectroscopy, atomic force microscopy (AFM), and gravimetric analysis. Raman spectra are consistent with the formation of NaHSO4 with no evidence for Na2SO4. The spectra indicate that the phase of NaHSO4 varies with the amount of H2O in the H2SO4. At low H2O concentrations, the reaction produces anhydrous β-NaHSO4, which undergoes a phase change to anhydrous α-NaHSO4 over the course of 18 h. At higher H2O concentrations, anhydrous α-NaHSO4 is formed with small amounts of NaHSO4·H2O. AFM measurements on NaCl (100) show the formation of two distinct types of NaHSO4 structures consistent in shape with α-NaHSO4 and β-NaHSO4. The β-NaHSO4 structures are mobile and move along the NaCl (110) plane until they encounter existing stationary α-NaHSO4 structures whereupon the two forms coalescence to form larger α-NaHSO4 structures. Gravimetry was used to determine the amount of HCl evolved upon exposure to aqueous H2SO4 solutions modeling atmospheric aerosols. At low H2SO4 concentrations, a large percentage of the HCl formed remains dissolved in the H2O. These results indicate that for conditions simulating relative humidities above 40%, the fraction of HCl released from this reaction may be as low as 0.40 ± 0.11.
• Pemberton, J. E., & Shen, A. (1999). Electrochemical and surface enhanced Raman scattering studies of bromide ion adsorption at silver electrodes in a series of normal alcohols. Physical Chemistry Chemical Physics, 1(24), 5671-5676.
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  Abstract: Br- surface coverage as a function of electrode potential is quantitatively determined using the Hurwitz-Parsons analysis of differential capacitance data at Ag electrodes in the series of normal alcohols, methanol through pentanol, containing LiBr. Values for the potential of zero charge (pzc) are estimated from these data. Surface-enhanced Raman spectroscopy (SERS) data in the ν(Ag-Br) region show the presence of a ν(Ag-Br) feature at potentials positive of the pzc which supports strong specific adsorption of Br- in these media. An excellent correlation between the SERS intensity and the Br- surface coverage determined from differential capacitance is observed. Bands attributed to hindered translational modes of trace interfacial water are also observed.
• Pemberton, J. E., Wood, L. L., & Ghoman, G. S. (1999). Determination of Surface Coverage of an Adsorbate on Silica Using FTIR Spectroscopy. Journal of Chemical Education, 76(2), 253-257.
• Schoenfisch, M. H., & Pemberton, J. E. (1999). Effects of Electrolyte and Potential on the in Situ Structure of Alkanethiol Self-Assembled Monolayers on Silver. Langmuir, 15(2), 509-517.
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  Abstract: Surface Raman spectroscopy using an emersion approach has been utilized to study the effects of electrolyte and applied potential on the in situ structure and conformational order of self-assembled monolayers (SAMs)formed from n-alkanethiols on smooth Ag surfaces. Vibrational information in the v(C-S), v(C-C), d(C-H), and v(C-H) regions is particularly useful in elucidating the degree of order and presence of defects in the monolayer before and after exposure of the SAM to electrolyte and potential. Spectral results from these studies suggest that aqueous 0.1 M electrolytes (NaF, NaCI, NaSCN, NaOH, H2SO4) and potential have different effects on the order of the SAMs studied. The order of short chain alkanethiol SAMs is more easily affected by electrolyte and potential than that of the longer chain SAMs.
• Shen, A., & Pemberton, J. E. (1999). Interfacial structure of dimethylsulfoxide at Ag electrodes from surface enhanced Raman scattering and differential capacitance. Journal of Electroanalytical Chemistry, 479(2), 21-31.
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  Abstract: Surface enhanced Raman scattering (SERS) and differential capacitance have been used to study interfacial structure in LiBr-containing dimethylsulfoxide (DMSO) at Ag electrodes. The potential-dependent orientation of this solvent is driven by interactions of the O atoms with the Ag surface at positive potentials and by interactions of the S atoms with the surface at negative potentials. Significant spectral changes are observed at potentials in the vicinity of the pzc indicating reorientation of interfacial solvent molecules. Evidence for unique potential-dependent interactions of Li+ and Br- with DMSO and trace amounts of H2O in the electrochemical interface have been uncovered on the basis of their spectral signatures. Potential-dependent molecular pictures of the interface in this system are proposed. © 1999 Elsevier Science S.A. All rights reserved.
• Shen, A., & Pemberton, J. E. (1999). Investigation of trace interfacial water at silver electrodes in a series of normal alcohols using surface enhanced Raman scattering. Physical Chemistry Chemical Physics, 1(24), 5677-5684.
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  Abstract: The behavior of trace interfacial water and its interaction with Li+ and Br- ions at Ag electrodes in the series of alcohols, methanol, ethanol, propanol, butanol and pentanol is studied using surface-enhanced Raman scattering (SERS). SERS spectra in the v(O-H) region exhibit four bands from the interfacial water species which are a sensitive function of the nature of the solvent, the residual water concentration and the electrode potential. These bands are assigned to water species interacting with specifically adsorbed Br-, Li+ in the outer Helmholtz plane, 'free' water species in the interface, or hydroxide in LiOH microcrystallites precipitated onto the electrode surface. Interfacial water molecules cluster around Li+ and Br- ions. The spectral data suggest pronounced restructuring of the water in the interface in the vicinity of the potential of zero charge.
• Shen, A., & Pemberton, J. E. (1999). Surface Raman scattering of interfaces at Ag electrodes emersed from dimethylsulfoxide: Spectroscopic evidence for an emersion-induced potential shift. Journal of Electroanalytical Chemistry, 479(2), 32-42.
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  Abstract: Surface Raman scattering has been used to study Ag electrodes emersed from LiBr solutions of dimethylsulfoxide (DMSO). Interfacial DMSO structure is generally similar to that in-situ, although spectral evidence for an emersion-induced potential shift is observed. The DMSO orientation at Ag electrodes is driven by interaction of the oxygen atom at potentials positive of the potential of zero charge (pzc) and the sulfur atom at potentials negative of the pzc. Pronounced restructuring of DMSO occurs in the vicinity of the pzc. Specific interactions between DMSO and electrolyte ions are clearly detected in the emersed interface. The observed potential shift is attributed to reorientation of the DMSO solvent dipoles at the emersed layer | gas interface. These results represent the first spectroscopic evidence for the existence of an emersion-induced potential shift. © 1999 Elsevier Science S.A. All rights reserved.
• Taylor, C. E., Pemberton, J. E., Goodman, G. G., & Schoenfisch, M. H. (1999). Surface enhancement factors for Ag and Au surfaces relative to Pt surfaces for monolayers of thiophenol. Applied Spectroscopy, 53(10), 1212-1221.
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  Abstract: Raman signal intensities from the 997 cm-1 ring breathing mode of thiophenol monolayers adsorbed at Ag, Au, and Pt surfaces were employed for determination of absolute surface enhancement factors (SEFs). Unlike previous estimations of SEFs, these SEFs are determined by referencing the surface-enhanced Raman scattering (SERS) intensities to the unenhanced Raman scattering at Pt surfaces. The surfaces studied include those commonly prepared in a laboratory ambient and those prepared in vacuum. Surfaces prepared in ambient include polycrystalline Ag electrochemically roughened by an oxidation-reduction cycle (ORC), mechanically polished (MP) polycrystalline Ag, chemically polished (CP) polycrystalline Ag, Ag (111), MP polycrystalline Au, and MP polycrystalline Pt. Vacuum environment surfaces include coldly deposited Ag films (cold Ag) and room temperature-deposited (RT) `thick' Ag films. Each of these thiophenol/metal systems was sampled with an excitation wavelength (λex) of 514.5 nm; MP Au surfaces were also studied with λex of 720 nm. SEFs of 2.0×104 for ORC Ag, 5.3×103 for MP Ag, 160 for cold Ag, 64 for MP Au720 (λex = 720 nm), 69 for Ag (111), 39 for CP Ag, 7.9 for RT `thick' Ag, and 2.2 for MP Au514.5 (λex = 514.5 nm) are observed relative to the SEF of MP Pt, which is assigned as 1. For practical purposes, the significance of the magnitudes of these SEFs is discussed in terms of estimated surface Raman limits of detection (LODs).
• Carter, D. A., Pemberton, J. E., & Woelfel, K. J. (1998). Orientation of 1- and 2-methylimidazole on silver electrodes determined with surface-enhanced raman scattering. Journal of Physical Chemistry B, 102(49), 9870-9880.
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  Abstract: Surface-enhanced Raman scattering is used to determine the potential-dependent orientation of 1- and 2-methylimidazole on Ag electrodes. Frequency shifts resulting from adsorption and potential changes suggest adsorption of these molecules through the pyridine nitrogen at positively charged surfaces. Unique v(CH3) features appear in the SERS spectra of 1-methylimidazole at neutral and negatively charged surfaces which suggest direct interaction of the methyl group with the surface. SERS surface selection rules are applied to three carefully selected groups of vibrational modes. The comparison of in-plane and out-of-plane ring modes is used to determine the orientations of the imidazole ring planes relative to the surface. The orientations of the methyl groups relative to the surface are elucidated by comparing the vsym(CH3) and vasym(CH3) modes. Finally, comparison of the v(N-CH3) to the δsym(N-CH3) of 1-methylimidazole and the v(C-CH3) to the δsym(C-CH3) of 2-methylimidazole provides information on the "side-to-side" tilting of these molecules. The orientation information thus obtained suggests that the methylimidazoles are attached to the electrode in a tilted orientation at potentials positive of the potential of zero charge (PZC), become more vertical as the potential approaches the PZC, and then are attached to the electrode primarily through the interaction of the methyl group at the most negative potentials. Pronounced "butterfly" waves in the cyclic voltammetry of these systems are interpreted in terms of adsorbate layer rearrangement. The potentials at which these processes occur are consistent with those at which spectral changes are observed.
• Mankit, H. o., & Pemberton, J. E. (1998). Alkyl chain conformation of octadecylsilane stationary phases by Raman spectroscopy. 1. Temperature dependence. Analytical Chemistry, 70(23), 4915-4920.
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  PMID: 21644674;Abstract: Raman spectroscopy is used for the first time to probe the effect of temperature on the conformational order of polymeric and monomeric octadecylsilane stationary phases. Spectral data in the v(C-C) and v(C-H) regions are interpreted in terms of alkyl chain conformational state and its dependence on temperature. In contrast to the liquid-like disordered state characteristic of these stationary phases at room temperature, at liquid N2 temperatures, the alkyl chains exist in a more ordered state with a residual level of gauche conformational defects. Systematic studies between -15 and 95 °C reveal more subtle changes in conformational order as ascertained from empirical spectral indicators including the intensity ratios I[v(a)(CH2)]/I[v(s)(CH2)] and I[v(C-C)(T)]/I[v(C-C)(G)]. Plots of these ratios as a function of temperature reveal two distinct regimes of behavior. By extrapolating the linear regions of these plots, a surface 'phase transition' temperature of ~20 °C for both surface-confined octadecylsilane stationary phases is estimated that represents subtle changes in alkyl chain conformational order from a more ordered phase to a slightly more disordered phase. The similarity in behavior between the polymeric and monomeric octadecylsilane stationary phases is interpreted as evidence for similar interchain spacing of the alkylsilanes on these silica surfaces.
• Schoenfisch, M. H., & Pemberton, J. E. (1998). Air stability of alkanethiol self-assembled monolayers on silver and gold surfaces. Journal of the American Chemical Society, 120(18), 4502-5413.
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  Abstract: Surface Raman spectroscopy, electrochemistry, and X-ray photoelectron spectroscopy have been used to study the effects of air exposure on the stability of self-assembled monolayers (SAMs) formed from alkanethiols on mechanically polished, smooth Ag and Au surfaces. Ramancspectra exhibit oxidized sulfur modes after only hours of air exposure. X-ray photoelectron spectroscopy of the S 2p region porvides additional evidence for sulfur oxidaton. Cyclic voltammetry of Ru(NH3)(3+) indicates that oxidized alkanethiol SAMs retain blocking characteristics toward electron transfer, even after exposure of the oxidized SAM-surface to a solubilizing solvent. Control experiments suggest ozone as the primary oxidant in ambient laboratory air which causes rapid oxidation of the thiolate moiety. These results have important ramification for the general use of SAms in many proposed application.
• Woelfel, K. J., & Pemberton, J. E. (1998). Determination of emersed electrochemical interface thickness by ellipsometry: Aqueous electrolytes on Ag. Journal of Electroanalytical Chemistry, 456(1-2), 161-169.
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  Abstract: An ellipsometric method for the determination of emersed electrochemical interfacial thickness at metal electrodes is reported. To demonstrate the effectiveness of this technique, a series of layers on Ag electrodes emersed from aqueous electrolytes are characterized. For most electrolytes, the measured thickness of the emersed interface is consistent with separation of the interface from bulk solution just outside of the outer Helmholtz plane. This behavior is discussed in terms of the various forces involved in structuring the electrochemical interface. © 1998 Elsevier Science S.A. All rights reserved.
• Zangmeister, C. D., & Pemberton, J. E. (1998). In situ monitoring of the NaCl + HNO₃ surface reaction: The observation of mobile surface strings. Journal of Physical Chemistry B, 102(45), 8950-8953.
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  Abstract: The reaction of single-crystal NaCl(100) with dry HNO3 was monitored using atomic force microscopy in contact mode. Initial exposure to dry HNO3 results in the growth of a two-dimensional metastable layer of NaNO3 to nearly complete surface coverage. Exposure of this metastable NaNO3 layer to small amounts of H2O produces deliquescence of the surface with concomitant rearrangement of the NaNO3 adlayer to form unusual mobile "strings" presumed to contain NaNO3. These strings are transient and eventually crystallize to form rhombohedral NaNO3 crystals sitting on top of the NaCl surface.
• Carter, D. A., & Pemberton, J. E. (1997). Raman spectroscopy and vibrational assignments of 1- and 2-methylimidazole. Journal of Raman Spectroscopy, 28(12), 939-946.
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  Abstract: Vibrational modes are assigned to the Raman bands of 1- and 2-methylimidazole. Assignments are based on a review of the literature assignments of imidazole, 1-methylimidazole and 4(5)-methylimidazole supplemented by Raman depolarization studies of 1.0 M solutions of 1- and 2-methylimidazole. Raman shifts observed for N-deuteration of 2-methylimidazole are also considered. © 1997 John Wiley & Sons, Ltd.
• Chamberlain, J. R., & Pemberton, J. E. (1997). Raman spectroscopy of Langmuir monolayers at the air-water interface. Langmuir, 13(12), 3074-3079.
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  Abstract: A new approach for the acquisition of Raman spectra of Langmuir layers at the air-water interface is presented. Colloidal Ag is grown electrochemically under layers of the anionic surfactants stearic acid and dipalmitoylphosphatidic acid sodium salt (DPPA) on an aqueous AgNO3 subphase. The Ag colloid layer supports surface-enhanced Raman scattering (SERS) of the Langmuir layers with minimal interference from the subphase. Spectra of good signal-to-noise ratio have been acquired. These spectra are interpreted in terms of the headgroup chemistry and the degree of alkane chain order as a function of surface pressure.
• Mankit, H. o., Cai, M., & Pemberton, J. E. (1997). Characterization of Octadecylsilane Stationary Phases on Commercially Available Silica-Based Packing Materials by Raman Spectroscopy. Analytical Chemistry, 69(13), 2613-2616.
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  PMID: 21639398;Abstract: Two commercially available solid phase extraction packing materials containing octadecylsilane stationary phases, Isolute C18MF and Isolute C18, were characterized using Raman spectroscopy. Raman spectra of excellent quality can be obtained from such systems and provide direct information about the alkyl chain conformation in the stationary phase. Data from the v(C-C) and v(C-H) spectral regions suggest that the alkyl chains of these stationary phases exist in a highly disordered state which is very similar to that of the neat liquid.
• Schoenfisch, M. H., Pemberton, J. E., Ovadia, M., & Levy, M. (1997). In Situ Electrochemistry of Ru(NH₃)³⁺₆ in a Perfused Rat Heart. Electroanalysis, 9(2), 135-140.
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  Abstract: Simple two-electrode potential sweep and potential step electrochemical measurements are reported in a perfused living rat heart prepared using a modified in situ Langendorff preparation. Cyclic voltammetry of Ru(NH3)3+6 at Pt electrodes is performed in vivo after retrograde aortic perfusion of Ca2+- and albumin-free, oxygenated Krebs buffer containing Ru(NH3)3+6 to assess uniformity of perfusion. Four types of voltammetric response are observed depending on the placement of the working electrode. These types are distinguished on the basis of the relative contributions of diffusive and hydrodynamic mass transport as manifest in the shapes of the current-potential curves. Chronoamperometric measurement of double layer charging was used to estimate extracellular tissue resistance. These chronoamperometric experiments are performed in buffer solutions by small potential steps around a set potential of non-Faradaic activity. Tissue resistance was estimated to be ca. 598 ± 138Ω from the chronoamperometric data. The electrochemical responses observed from both measurements exhibit good reproducibility between individual heart preparations.
• Thompson, W. R., Cai, M., Mankit, H. o., & Pemberton, J. E. (1997). Hydrolysis and condensation of self-assembled monolayers of (3-mercaptopropyl)trimethoxysilane on Ag and Au surfaces. Langmuir, 13(8), 2291-2302.
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  Abstract: Self-assembled monolayer films of (3-mercaptopropyl)trimethoxysilane (3MPT) and their hydrolysis products on Ag and Au surfaces are characterized using Raman spectroscopy, FTIR spectroscopy, ellipsometry, X-ray photoelectron spectroscopy (XPS), and electrochemistry. 3MPT monolayers are formed through metal-thiolate bonding through the S atom on both metals, similar to other alkanethiol chemisorption chemistries. The orientation of 3MPT molecules in these monolayers is similar on both metals. Prior to hydrolysis, the molecules form an organized monolayer with the methoxy headgroups oriented largely parallel to the surface and the propyl chain in a largely trans conformation. When the methoxy groups are hydrolyzed, the 3MPT molecules cross-link through the formation of siloxane bonds. Although the surface vibrational spectroscopy indicates the presence of a small number of unreacted silanol groups on the siloxane surface, cyclic voltammetry of underpotential deposition of Pb suggests that the Si-O-Si network is highly cross-linked and relatively free from gross defects. The number of these unreacted silanols is estimated using XPS to be fewer than 5% of the original Si-O sites in the 3MPT monolayer.
• Pemberton, J. E., & Garvey, S. D. (1996). Spectroscopic methods for the characterization of electrochemical interfaces and surfaces. Chemical Analysis, 139, 59-106.
• Pemberton, J. E., Joa, S. L., Shen, A., & Woelfel, K. J. (1996). Interfacial solvent structure in butan-1-ol, butan-2-ol and 2-methylpropan-1-ol at Au and Ag electrodes from surface enhanced Raman scattering and capacitance measurements. Journal of the Chemical Society - Faraday Transactions, 92(20), 3683-3691.
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  Abstract: Surface enhanced Raman scattering (SERS) and differential capacitance have been used to study interfacial solvent structure in LiBr electrolyte solutions of three isomers of butanol, butan-1-ol, butan-2-ol and 2-methylpropan-1-ol, at Au electrodes. The potential-dependent spectral behaviour in the regions containing the v(C-C), v(C-O) and v(C-H) modes of these isomers at Au electrodes is compared to that observed at Ag electrodes as a function of rational potential. Differential capacitance data are treated using the Hurwitz-Parsons analysis to extract surface coverage of specifically adsorbed Br- as a function of electrode potential. Potential of zero charge (p.z.c.) values are estimated from these data. Based on a quantitative comparison of spectral data at Ag and Au electrodes as a function of rational potential, the solvent structures at Au electrodes are concluded to resemble those previously proposed for Ag electrodes. The potential-dependent orientations of these solvents appear to be driven by interactions of the O non-bonding electrons and the alkyl chain with the electrode, and hydrogen bonding of the hydroxy group with specifically adsorbed Br-. At potentials positive of the p.z.c. at both metals, butan-1-ol and butan-2-ol hydrogen bond with specifically adsorbed Br- with their alkyl portions relatively close to the electrode surface. As more negative potentials are applied, Br- is repelled from the surface, and the alkyl groups move away from the electrode surface insofar as is possible. Only minor changes in orientation are observed as a function of potential for 2-methylpropan-1-ol at these electrodes due to the symmetry of its alkyl structure. The interaction of the O atom of 2-methylpropan-1-ol with the electrode is similar to that observed for the other butanol isomers. This interaction places the alkyl groups of the molecule at the surface in an orientation which is largely potential-insensitive.
• Taylor, C. E., Garvey, S. D., & Pemberton, J. E. (1996). Carbon Contamination at Silver Surfaces: Surface Preparation Procedures Evaluated by Raman Spectroscopy and X-ray Photoelectron Spectroscopy. Analytical Chemistry, 68(14), 2401-2408.
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  Abstract: The quantity and chemical nature of carbonaceous impurities remaining on polycrystalline Ag surfaces after preparation depend on the protocol used for cleaning. The effectiveness of several preparation protocols was investigated in this study: mechanical polishing with successively finer grades of alumina, Ar+ sputtering, chemical polishing, and chemical polishing followed by T1 underpotential deposition. The impurities detected on polycrystalline Ag surfaces subjected to these preparation procedures are carbon, oxygen, and aluminum, and these are qualitatively and quantitatively identified with X-ray photoelectron spectroscopy. With Raman spectroscopy, these carbonaceous impurities are qualitatively identified as graphite, hydrocarbon, and cyanide species, the last of these being present only on the chemically polished surfaces.
• Carter, D. A., & Pemberton, J. E. (1995). Wavelength Calibration of Multipurpose Multichannel Raman Spectrometers. Part I: Instrumental Factors Affecting Precision. Applied Spectroscopy, 49, 1550-1560.
• Carter, D. A., & Pemberton, J. E. (1995). Wavelength Calibration of Multipurpose Multichannel Raman Spectrometers. Part II: Calibration Standards and Calibration Fit Considerations. Applied Spectroscopy, 49, 1561-1576.
• Thompson, W. R., & Pemberton, J. E. (1995). Characterization of octadecylsilane and stearic acid layers on Al2O3 surfaces by Raman spectroscopy. Langmuir, 11(5), 1720-1725.
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  Abstract: Results are presented which demonstrate the use of Raman spectroscopy for the characterization of octadecylsilane, octadecyldimethylsilane, and stearic acid layers on Al2O3 surfaces without the use of surface enhancement. Unlike previous attempts to study adsorbates at Al2O3 surfaces, an enhancing Ag adlayer was not used. These results represent the first report of the use of Raman spectroscopy for the characterization of alkylsilane and stearic acid layers on Al2O3 surfaces. The spectral data are interpreted in terms of alkyl chain conformation within these layers. Raman data from the v(C-C) and v(C-H) spectral regions suggest that the alkyl chains comprising the octadecylsilane layer are more disordered than similar films formed on silica. The octadecyldimethylsilane monolayers are less ordered, suggesting an even greater concentration of gauche conformations in the alkyl chains of these films. The observed increase in disorder in films formed from octadecyldimethylsilane is attributed to the influence of the bulky methyl groups on bonding density which prevent the alkyl chains from packing at their van der Waals radii. The Raman spectral data from self-assembled films formed from stearic acid suggest that these films are more ordered than the similar films from alkylchlorosilanes. The increase in order is believed to be due to the bonding orientation of the carbonyl group at the Al2O3 surface. © 1995 American Chemical Society.
• Thompson, W. R., & Pemberton, J. E. (1995). Thin sol-gel silica films on (3-mercaptopropyl)trimethoxysilane-modified Ag and Au surfaces. Chemistry of Materials, 7(1), 130-136.
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  Abstract: The results presented here demonstrate the utility of (3-mercaptopropyl)trimethoxysilane (3MPT) for attachment of a strongly adherent thin layer of silica to Ag and Au surfaces. The thin silica surfaces are formed by standard sol-gel procedures and are shown to be representative of other silica systems. The basis of the adhesion between these two surfaces is covalent bonding between the 3MPT and both the metal and the silica. If 3MPT is not used, the thin silica layer is poorly adherent to the Au surface and only moderately adherent to the Ag surface. Ellipsometry, X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, and qualitative and quantitative adhesion tests are used to characterize this system.
• Matzner, R. A., Bales, R. C., & Pemberton, J. E. (1994). In situ Raman spectroscopy of aza-arenes adsorbed at the aqueous/silica interface. Applied Spectroscopy, 48(9), 1043-1053.
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  Abstract: Raman spectroscopy is used to study the effect of pH on the solute/sorbent interactions and the chemical nature of the adsorbed species at the aqueous/silica interface for the aza-arenes acridine, quinoline, and pyridine. The neutral aza-arene is hydrogen-bonded to surface sites in aqueous media in which the pH is above the pKa of the compound. A protonated aza-arene/ClO4 ion pair interacts with surface sites in aqueous solutions in which the pH is below the pKa of the compound. These results may be useful in predicting the fate of these environmentally significant compounds in groundwater.
• Pemberton, J. E., & Joa, S. L. (1994). Water and electrolyte structure at Ag electrodes in nonaqueous butanol solutions using surface-enhanced Raman scattering. Journal of Electroanalytical Chemistry, 378(1-2), 149-158.
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  Abstract: Surface-enhanced Raman scattering (SERS) has been used to investigate the interfacial H2O and electrolyte behavior of LiCl, LiBr, LiI and LiClO4 at Ag electrodes in several isomers of butanol, including 1-butanol, iso butanol and 2-butanol. The ν(OH) region contains bands originating from trace H2O that are clearly indicative of the behavior of the electrolyte in the interfacial region. Six ν(OH) bands are observed in the surface spectra depending on the electrode potential. These are assigned on the basis of previous assignments made for similar bands in aqueous solutions and the spectral response of crystalline LiOH. The intensities of these bands are a function of the nature of the anion in the LiX electrolyte, the particular isomer of butanol used as the solvent and the electrode potential. A band at ca. 3500 cm-1 is assigned to H2O hydrogen-bonded to specifically adsorbed anions at the electrode surface at potentials positive of the potential of zero charge (pzc). A band assigned to H2O in the primary solvation shell of the Li+ is observed at ca. 3570 cm-1 at potentials negative of the pzc. A band thought to be due to "free" H2O not associated with specific ions, perhaps weakly held in the secondary solvation shell of Li+, is observed between 3600 and 3650 cm-1. Up to three bands are observed from OH- formed at the electrode during the reduction of H2O at negative potentials. At these potentials, a band observed at 3600 cm-1 is assigned to OH- weakly involved with Li+, perhaps in a solvent-separated ion pair. A second OH- band observed at ca. 3630 cm-1 is assigned to OH- species adsorbed through the oxygen atom to the Ag electrode surface. The sharp band observed at ca. 3660 cm-1 is assigned to crystalline LiOH species which form owing to the poor solubility of this salt in the isomers of butanol. This compound is either precipitated on the electrode surface or found as microcrystallites in the interfacial region. © 1994.
• Thompson, W. R., & Pemberton, J. E. (1994). Raman spectroscopy of covalently bonded alkylsilane layers on thin silica films immobilized on silver substrates. Analytical Chemistry, 66(20), 3367-3370.
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  Abstract: Results are presented which demonstrate the use of Raman spectroscopy for the characterization of alkylsilane layers covalently bound to silica surfaces. Raman spectra of molecular assemblies of octadecylsilane have been studied by use of a thin silica gel/Ag sandwich structure as the substrate. The Ag surface, used to provide electromagnetic enhancement to the octadecylsilane overlayer, is modified with a monolayer of (3-mercaptopropyl)trimethoxysilane, which is used as a molecular adhesive for anchoring the thin silica gel film. Spin coating a silica sol on the modified Ag surface results in the formation of a thin silica gel layer which contributes minimal fluorescence background to the Raman spectra. The spectral data have been interpreted in terms of the alkyl chain conformation within a layer of octadecylsilane, used as a model of a reversed-phase Chromatographic stationary phase, on dry silica surfaces as well as in the presence of solvents commonly used in chromatograpby. The Raman data from the v(C-C) and v(C-H) spectral regions suggest that the alkyl chains comprising the layer are predominantly in an ordered configuration. These data represent the first Raman spectra reported for alkylsilane layers on oxide surfaces and demonstrate the feasibility of acquiring conformational information from alkylsilane layers covalently bound to silica surfaces.
• Joa, S. L., & Pemberton, J. E. (1993). Surface Raman scattering of the butanol isomers on emersed Ag and Au electrodes. Journal of Physical Chemistry, 97(37), 9420-9424.
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  Abstract: Surface Raman scattering in the ν(C-H) region of 1-butanol, 2-butanol, and isobutyl alcohol on emersed rough and smooth Ag and Au electrodes is reported and is compared to the corresponding in-situ surface-enhanced Raman scattering results. Identical spectral behavior is observed for the rough and smooth emersed electrodes compared to the in-situ electrodes, suggesting that the solvent structure and orientation at the electrode is retained upon emersion. The behavior of the ν(Au-Br) band and the ν(O-H) band from interfacial water solvating ions suggests that the electrolyte structure is also retained upon emersion. The stability of the emersed layer is extremely dependent on solvent evaporation, atmospheric purity, and electrode contamination. A new spectroelectrochemical cell that allows routine collection of spectra from emersed smooth and rough electrodes is also described. © 1993 American Chemical Society.
• Thompson, W. R., & Pemberton, J. E. (1993). Surface Raman scattering of self-assembled monolayers of (3-mercaptopropyl)trimethoxysilane on silver: Orientational effects of hydrolysis and condensation reactions. Chemistry of Materials, 5(3), 241-244.
• Bryant, M. A., Joa, S. L., & Pemberton, J. E. (1992). Raman scattering from monolayer films of thiophenol and 4-mercaptopyridine at Pt surfaces. Langmuir, 8(3), 753-756.
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  Abstract: Surface Raman spectra have been successfully acquired from monolayer films of thiophenol and 4-mercaptopyridine adsorbed at mechanically polished, polycrystalline Pt surfaces. Surface coverages for thiophenol on these Pt surfaces were estimated from X-ray photoelectron spectroscopy and electrochemical studies. This work demonstrates the feasibility of studying surface chemistry occurring on Pt surfaces using Raman spectroscopy.
• Carter, D. A., & Pemberton, J. E. (1992). Surface-enhanced Raman scattering of the acid-base forms of imidazole on Ag. Langmuir, 8(4), 1218-1225.
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  Abstract: Surface-enhanced Raman scattering (SERS) of adsorbed imidazole-(pH 9) and the imidazolium ion (pH 2) on Ag electrodes is reported and compared to the normal Raman spectra of the corresponding solution and solid species. Changes in frequency and relative intensity of the imidazole bands upon adsorption and as a function of potential are consistent with imidazole adsorption primarily through the pyridine N. Some interaction of the C=N π orbital with Ag is also suggested. Consideration of surface selection rules suggests that the imidazole is tilted with respect to the surface normal at potentials positve of the potential of zero charge and assumes a more vertical orientation as the potential is made more negative. Photolysis intense SERS bands are observed when using imidazole that has not been rigorously purified. These are proposed to be due to an impurity present in the imidazole supplied by a number of manufacturers. These bands have been previously misinterpreted as unique imidazole surface species. The SERS response of the imidazolium ion to changes in the electrode potential is consistent with imidazolium coadsorption with the chloride ion.
• Ingram, J. C., & Pemberton, J. E. (1992). Comparison of charge transfer enhancement in the surface enhanced Raman scattering of pyridine on copper and silver electrodes. Langmuir, 8(8), 2034-2039.
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  Abstract: The object of the experiments described here is to compare the charge transfer (CT) excitation of surface enhanced Raman scattering (SERS) from pyridine adsorbed on Cu and Ag electrodes. The CT excitation is probed by varying both the applied potential and the excitation energy. SERS intensity-potential profiles of pyridine on Cu electrodes using excitation wavelengths of 620, 720, and 1064 nm and on Ag electrodes using excitation wavelengths of 580, 620, and 720 nm are presented. The maximum intensities displayed in these profiles for the two metals occur at similar applied potentials. However, these profiles differ from those predicted on the basis of the potential-dependent adsorption behavior of pyridine on Cu and Ag electrodes. These results are discussed in term of the energetics of the CT bands for pyridine on Cu and Ag electrodes. The energy position and width of the CT band can be determined from the SERS intensity-potential profiles. Although the CT bands are energetically similar for both electrodes, the energy width of the Ag CT band is ca. 65% less than the energy width of the Cu CT band suggesting that the CT sites on Cu are energetically more heterogeneous that those on Ag.
• Ingram, J. C., & Pemberton, J. E. (1992). Investigation of the quenching of surface enhanced Raman scattering from pyridine on copper and silver electrodes by underpotential deposition of lead. Langmuir, 8(8), 2040-2048.
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  Abstract: Experiments designed to investigate the effect of the underpotential deposition (UPD) of Pb on the surface enhanced Raman scattering (SERS) of pyridine adsorbed on Cu electrodes are described. Drawing on the wealth of information published on the SERS of Ag, the approach taken in these studies is to directly compare the SERS response of Cu to AG under similar conditions. An excitation study of the SERS quenching of pyridine adsorbed at these electrodes by Pb UPD is presented. The quenching of Cu SERS at different excitation energies does not emulate the previously reported AG response. Both electromagnetic (EM) and charge transfer (CT) mechanisms are considered in interpreting this behavior. Optical property measurements as well as EM enhancement calculations based on a model described by Murray for PB submonolayer films on Cu and Ag are discussed. The EM predicted quenching behavior is inadequate in explaining the experimental results. The CT predictions, however, correlate well to the results. Further investigation of the quenching differences of the two systems through negative potential excursion studies reveals an increased stability of the Cu CT sites relative to those of Ag. The differences observed in the quenching profiles of the two systems are attributed to the increased stability of the Cu CT sites.
• Joa, S. L., & Pemberton, J. E. (1992). Surface enhanced Raman scattering investigation of interfacial structure at Ag electrodes in electrolyte solutions of the isomers of butanol. Langmuir, 8(9), 2301-2310.
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  Abstract: Surface enhanced Raman scattering has been used to study the interfacial solvent structure of three of the isomers of butanol, 1-butanol, 2-butanol, and 2-methyl-1-propanol (isobutyl alcohol), at Ag electrodes in butanol electrolyte solutions. These alcohols interact with the Ag electrode through the O atom. Orientational information is obtained for these solvents by monitoring the v(C-C), v(C-O), v(C-H), v(Ag-Br), and v(O-H) regions of the SERS spectra as a function of electrode potential. The alcohol orientations appear to be driven by both the O lone pair and alkane chain interactions with the electrode surface. At positive potentials, 1-butanol is largely parallel to the Ag surface. The alkane end of this alcohol is repelled from the electrode as more negative potentials are applied. The O interaction of 2-butanol at the electrode surface is similar to that for 1-butanol. Additionally, the ethyl unit of 2-butanol is driven away from the electrode surface at negative potentials. Only one orientation is observed for 2-methyl-1-propanol as a function of potential. Again, the interaction of the O with the surface is similar to that of the other two isomers. Interfacial water, existing as a trace impurity in these nonaqueous environments, was also monitored and found to exhibit interesting potential-dependent behavior at these electrodes that might be a useful indicator of the potential of zero charge.
• Pemberton, J. E., Bryant, M. A., Joa, S. L., & Garvey, S. D. (1992). Surface Raman scattering of organic thin films on transition metal surfaces. Proceedings of SPIE - The International Society for Optical Engineering, 1636, 108-116.
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  Abstract: Recent advances in detector technology have enabled sensitivity limitations inherent in surface Raman scattering from thin organic films on metal surfaces to be overcome. The application of both surface enhanced Raman scattering and normal Raman scattering of organic monolayer films on metal surfaces in electrochemical and ambient environments is an area of active research in this laboratory. The use of surface selection rules for the development of detailed molecular pictures of these interfaces is discussed in this report. The application of these rules for determination of the orientation of self-assembled monolayers on Ag and Au surfaces in both electrochemical and ambient environments is used to demonstrate the approach. In addition, extension of surface Raman methods to the study of monolayer organic films on Pt surfaces is reported.
• Pemberton, J. E., Bryant, M. A., Sobocinski, R. L., & Joa, S. L. (1992). A simple method for determination of orientation of adsorbed organics of low symmetry using surface-enhanced Raman scattering. Journal of Physical Chemistry, 96(9), 3776-3782.
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  Abstract: A simple method for the determination of the orientation of low-symmetry adsorbates on metal surfaces supporting surface-enhanced Raman scattering by predominantly the electromagnetic mechanism is presented. This method is based on the modification of the isotropic intensity ratio of two vibrational modes of known spatial relation of the molecule by the total electric field, and hence radiation intensity, existing at the metal surface. This total radiation field represents the vector sum of the components normal and tangential to the metal surface, both of which exist for radiation in the visible-wavelength region. The validity of this method is demonstrated for methanol adsorbed on Ag surfaces through the use of the symmetric and asymmetric v(C-H) vibrations. Application of this approach to a series of molecules containing four carbon units and methyl groups (1-butanol, 2-butanol, isobutanol, 1-butanethiol, and 2-butanethiol adsorbed on Ag surfaces and 1-butanethiol adsorbed on Au surfaces) is reported. © 1992 American Chemical Society.
• Rolison, D. R., Thiel, P. A., Stacy, A. M., Richmond, G. L., Rice, J. K., Pemberton, J. E., Osteryoung, J. G., O'Grady, W. E., Nowak, R. J., & Lichter, R. L. (1992). Women in science: The response [16]. Science, 256(5064), 1614-1615.
• Sobocinski, R. L., & Pemberton, J. E. (1992). Determination of alcohol solvent orientation and bonding at silver electrodes using surface-enhanced Raman scattering: methanol, ethanol, 1-propanol, and 1-pentanol. Langmuir, 8(8), 2049-2063.
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  Abstract: Interfacial solvent structure at Ag electrodes in various straight-chain alcohol electrolyte systems has been studied using surface-enhanced Raman scattering (SERS). SERS provides detailed information regarding the nature of interfacial bonding and alkyl chain orientation. Methanol appears to be in a unique hydrogen-bonding environment at the interface, as indicated by a 10-cm-1 decrease in ν(C-O) frequency from its bulk solution value; C2 and longer chain alcohols at the interface show no shift in ν(C-O) frequency from bulk solution. The alkyl chains are largely parallel to the surface (i.e., greater than 45° relative to the surface normal) and exist in a largely all-trans configuration at electrode potentials positive of the PZC (potential of zero charge). These molecules are oriented with the hydroxyl group at the surface and the alkyl chain tilted slightly away from the surface. At more negative potentials near the PZC, the alkyl chain conformations become more disordered, and the alkyl chains 'stand up', with the methyl group directed into bulk solution. For methanol, two distinct orientations exist simultaneously at the interface in the vicinity of the PZC. The growth of a new methylene band for C2, C3, and C5 alcohols at increasingly negative potentials suggests significant interaction of the methylene hydrogens with the surface. In contrast to the C3 and C5 alcohols, the C1 and C2 alcohols exhibit little bulk spectroscopic behavior, indicating distinct orientations at potentials negative of the PZC.
• Blackbourn, R. L., Johnson, C. S., Hupp, J. T., Bryant, M. A., Sobocinski, R. L., & Pemberton, J. E. (1991). A complete experimental assessment of Franck-Condon structural effects for an irreversible outer-sphere electron-transfer reaction: Applications of time-dependent Raman scattering theory to the one-electron reduction of 4-cyano-N-methylpyridinium. Journal of Physical Chemistry, 95(26), 10535-10537.
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  Abstract: A complete experimental description of the vibrational Franck-Condon barrier to the one-electron reduction of 4-cyano-N-methylpyridinium cation (NC-py-CH3+) has been obtained. Because of the chemical irreversibility of the electron transfer, the reaction is not readily amenable to study by conventional structural methods. The approach successfully employed here, however, was a time-dependent analysis of near-resonant Raman scattering where resonance was achieved by pairing the cation to iodide anion; the pairing gives rise to a weak (ε = 565 M-1 cm-1) outer-sphere charge-transfer band centered at 428 nm in acetonitrile as solvent. The time-dependent analysis of scattering yields vibrational frequencies, coordinate displacements, and single-mode barrier contributions for each of 13 modes involved in outer-sphere electron transfer. Depolarization measurements, excitation profiles, and scattering studies with the nonchromophoric [NC-py-CH3+,Cl-] ion pair confirm that the vibrational structural data pertain directly to the outer-sphere charge-transfer reaction rather than to higher lying electronic transitions. © 1991 American Chemical Society.
• Bryant, M. A., & Pemberton, J. E. (1991). Surface Raman Scattering of Self-Assembled Monolayers Formed from 1-Alkanethiols: Behavior of Films at Au and Comparison to Films at Ag. Journal of the American Chemical Society, 113(22), 8284-8293.
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  Abstract: Surface Raman scattering is used to study self-assembled monolayers formed from a series of 1-alkanethiols, CH3(CH2)nSH, where n = 3-5, 7, 8, 11, and 17, at mechanically polished and electrochemically roughened Au surfaces. Defect structure in these films is investigated by use of the relative intensities of peaks due to trans and gauche conformations in the ν(C-S) and ν(C-C) frequency regions. Surface selection rules for Raman spectroscopy are used to estimate orientation of the alkanethiol layers at Au. The orientation proposed on the basis of the Raman spectral data is consistent with those previously reported on the basis of other measurements at Au surfaces. This orientation is compared to that previously determined for these films at Ag. Alkanethiols at Ag are found to have a chain tilt from the surface normal less than the 30° previously reported for Au. The C-S bond is found to be perpendicular to the Ag surface while it is largely parallel to the surface at Au. Differences in the spectra of short-chain alkanethiols from smooth and rough surfaces are attributed to disordering of the film at the roughened Au surface which occurs predominantly near the S end of the molecule on rough Au surfaces.
• Bryant, M. A., & Pemberton, J. E. (1991). Surface Raman scattering of self-assembled monolayers formed from 1-alkanethiols at Ag. Journal of the American Chemical Society, 113(10), X-3637.
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  Abstract: Surface Raman scattering is used to study self-assembled monolayers formed from a series of 1-alkanethiols (1-butanethiol, 1-dodecanethiol, 1-octadecanethiol) at both electrochemically roughened and mechanically polished polycrystalline Ag electrodes. The spectra obtained at both surfaces are similar in all spectral regions. Defect structure in these films is investigated using the relative amounts of trans and gauche conformers in the v(C-S) and v(C-C) frequency regions. These monolayer films are most ordered in the cases of 1-butanethiol and 1-octadecanethiol and least ordered in the case of 1-dodecanethiol. This behavior correlates with the ordering observed in the bulk 1-alkanethiols. Surface selection rules are used to determine molecular orientation at Ag.
• Pemberton, J. E., & Sobocinski, R. L. (1991). Raman spectroscopy of the emersed Ag | alcohol electrochemical interface. Journal of Electroanalytical Chemistry, 318(1-2), 157-169.
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  Abstract: Raman spectroscopy is used to characterize the molecular structure and orientation of the solvent in electrochemical interfaces at Ag electrodes emersed from methanol and 1-propanol electrolyte solutions. The vibrational behavior of the solvent in the emersed interfaces is compared with that existing in situ as probed by surface enhanced Raman scattering as a function of electrode potential. Changes in peak frequency shifts and relative intensities as a function of potential are maintained upon emersion of the electrode from the alcohol electrolyte solution. These observations suggest that both solvent orientation and bonding environment at the Ag surface remain unperturbed by the emersion process. Additionally, the solvent behavior upon emersion is compared at rough and smooth Ag surfaces. The similarity in the spectra from these two types of surfaces as a function of potential suggests that surface enhanced Raman scattering can provide information about the average interfacial solvent molecules in electrochemical systems. © 1992.
• Pemberton, J. E., Latifzadeh, L., Fletcher, J. P., & Risbud, S. H. (1991). Raman spectroscopy of calcium phosphate glasses with varying CaO modifier concentrations. Chemistry of Materials, 3(1), 195-200.
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  Abstract: Raman spectroscopy has been performed on a series of calcium phosphate glasses prepared from calcium dihydrogenphosphate and CaO in which the CaO content is varied from that of the metaphosphate stoichiometry, in which the mole ratio of CaO to P2O5 is 1.00, to a stoichiometry in which the mole ratio is 1.49. Investigation of the vibrational behavior provides insight into the effects of the CaO modifier on the depolymerization processes occurring in these phosphate glasses. Curve-fitting procedures are used to accurately identify peak positions and resolve overlapped bands in the spectra. Depolymerization of the phosphate chains is clearly observed in the vibrational spectra as indicated by shifts in the νs(POP), νs(PO2), and νas(PO2) vibrations. At the largest CaO modifier concentrations, distinct crystalline phases of α- and γ-Ca2P2O7 are observed. Analysis of the Raman spectra for these systems suggests that crystallization occurs from the short chain regions of the glass. © 1991 American Chemical Society.
• Phule, P. P., Risbud, S. H., & Pemberton, J. E. (1991). Sol-Gel Synthesis and Characterization of Barium Polytitanates in the BaO-TiO2 System. Advances in Ceramics, 10, 324-329.
• Bryant, M. A., & Pemberton, J. E. (1990). Differential reflectance spectroscopy and SERS of mildly roughened silver electrodes. Langmuir, 6(4), 751-758.
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  Abstract: Differential reflectance spectroscopy has been used to measure the reflectivity of electrochemically roughened Ag electrodes in 0.1 M KCl and 0.1 M KCl/0.05 M pyridine. The electrodes were subjected to varying anodic current densities in double-potential-step oxidation-reduction cycles. A correlation exists in both systems between SERS intensities for both v(Ag-Cl) and pyridine ring breathing vibrations and the magnitude of the decrease in reflectivity. Surfaces that exhibit the greatest decrease in reflectivity exhibit the greatest SERS intensity. Scanning electron microscopy is used to characterize surface morphology. The reflectivity spectra are interpreted in terms of absorption by large-scale Ag roughness features. The correlation between decrease in reflectivity and increased SERS intensity is proposed to be due to electromagnetic enhancement effects. © 1990 American Chemical Society.
• Ingram, J. C., Nebesny, K. W., & Pemberton, J. E. (1990). Optical constants of the noble metals determined by reflection electron energy loss spectroscopy. Applied Surface Science, 44(4), 293-300.
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  Abstract: The optical constants for Cu, Ag, and Au determined by reflection electron energy loss spectroscopy (REELS) using a data treatment method described in the previous paper in this Journal are reported. The purpose of this study is to further test the data treatment method on less free-electron-like metals. The method involves removal of surface effects by deconvolution of data taken with low-energy electrons (200 eV) from data taken with higher energy electrons (1500 eV). The low- and high-energy electron experimental spectra are discussed along with the resulting optical constants. It is found that, although the surface loss contribution to the high-energy electron data is not readily apparent, its contribution does affect the results of the Kramers-Kronig analysis used to determine the complex dielectric function. Thus, some account must taken of the surface loss contribution in order to obtain quantitative information about the optical constants. Along with surface effects, plural-scattering contributions to the spectral response are also removed using deconvolution procedures. Comparison of these results to literature values demonstrates that the data treatment method is successful in closely approximating the optical constants for Cu, Ag, and Au. © 1990.
• Ingram, J. C., Nebesny, K. W., & Pemberton, J. E. (1990). Optical properties of metal surfaces from electron energy loss spectroscopy in the reflection mode. Applied Surface Science, 44(4), 279-291.
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  Abstract: The development and evaluation of a method to determine optical constants using electron energy loss spectroscopy (EELS) in the reflection mode is reported. An empirical approach is taken in these studies in order to minimize the necessity for a-priori information concerning the sample of interest. The goal of this research is to determine optical constants of metal systems using a standard electron spectrometer and very little sample preparation. The data treatment involves isolating the loss function from the experimental EEL spectrum by (a) deconvolution of the surface plasmon contribution from the data obtained with a high-energy primary beam using data acquired with a low-energy primary beam at a grazing incidence angle, (b) minimization of the plural scattering contribution through deconvolution of a model spectrum obtained experimentally, and (c) removal of the dispersion contribution through deconvolution of a theoretical dispersion function. The complex dielectric function is obtained through a Kramers-Kronig analysis of the isolated loss function. The results for Al acquired with several primary beam energies are presented and compared to literature values. These results indicate that the proposed method is most successful for determining the dielectric function of Al when primary beam energies of 1500 eV or greater are employed. The results also suggest that dispersion effects can be minimized experimentally using primary beams of relatively high energy. © 1990.
• Ingram, J. C., Nebesny, K. W., & Pemberton, J. E. (1990). Optical properties of selected first-row transition metals determined by reflection electron energy loss spectroscopy. Applied Surface Science, 45(3), 247-256.
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  Abstract: The optical constants for Ti, V, Fe, Co, and Ni determined by reflection electron energy loss spectroscopy (REELS) are reported. The optical constants were calculated from the experimental REELS data using an empirical data treatment method previously reported [Appl. Surf. Sci. 44 (1990) 279, 293]. The purpose of this study is to further evaluate the data treatment method on electronically more complex metals. The REELS experimental spectra, taken with primary beam energies of 1500 and 200 eV, are discussed along with the resulting optical constants. These results are compared to values reported in the literature. From this comparison, it is shown that the method is effective in approximating the real (ε{lunate}1) and imaginary (ε{lunate}2) parts of the dielectric constant for Ti, V, Fe, Co, and Ni. © 1990.
• Pemberton, J. E., Sobocinski, R. L., & Sims, G. R. (1990). Effect of charge traps on Raman spectroscopy using a Thomson-CSF charge coupled device detector. Applied Spectroscopy, 44(2), 328-330.
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  Abstract: Charge coupled device (CCD) detectors have seen increasing use in analytical spectroscopy in recent years. One of the more popular scientific-grade CCD detectors on the market is the Thomson-CSF TH7882CDA. However, the TH7882 CCD suffers from a phenomenon known as a charge 'trap' associated with the interface between the serial and parallel registers. This trap causes absorption, emission, and mixing of charge passing through this interface depending in a complex manner upon both the quantity of charge in the trap and the quantity of charge entering the trap. The effect of this charge trap on the resulting spectral response for very low-light-level applications is demonstrated here. It has been shown that for three of the four types of cellulose studied, an infrared analysis technique has been developed which can determine whether embrittlement of the cellulose has occurred. This technique was successfully used in the search for new embrittling reagents.
• Pemberton, J. E., Sobocinski, R. L., Bryant, M. A., & Carter, D. A. (1990). Raman Spectroscopy Using Charge Coupled Device Detection. Spectroscopy International, 4, 26-36.
• Pemberton, J. E., Sobocinski, R. L., Bryant, M. A., & Carter, D. A. (1990). Raman Spectroscopy with Charge-Coupled Device Detection. Spectroscopy, 5, 26-36.
• Sobocinski, R. L., & Pemberton, J. E. (1990). SERS investigation of interfacial methanol at silver electrodes. Langmuir, 6(1), 43-50.
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  Abstract: Interfacial solvent structure at Ag electrodes in methanol electrolyte systems has been studied by using surface-enhanced Raman scattering (SERS). The potential dependence of the SERS response suggests that methanol interacts with Ag electrodes through the oxygen end of the molecule. At all potentials studied, the C-O bond appears to remain largely parallel to the surface. It is proposed that at potentials positive of the PZC only one oxygen p-orbital is directed toward the Ag surface. Near the PZC, it is postulated that two methanol orientations are detected simultaneously in the presence of Li+. Evidence is presented for the influence of supporting electrolyte cation and anion on the orientation of methanol at these electrodes.
• Sobocinski, R. L., Bryant, M. A., & Pemberton, J. E. (1990). Surface Raman scattering of methanol, 1-propanol, 1-pentanol, and 1-butanethiol on in situ and emersed silver electrodes. Journal of the American Chemical Society, 112(17), 6177-6183.
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  Abstract: Surface Raman scattering is used to study the adsorption of several straight-chain alcohols (methanol, 1-propanol, 1-pentanol) and a straight-chain alkanethiol (1-butanethiol) at Ag electrodes. Surface-enhanced Raman scattering (SERS) studies are carried out on both in situ and emersed roughened electrodes. Normal surface Raman scattering is performed on mechanically polished, mirrored polycrystalline electrodes that have been emersed from solution. It is generally observed that the Raman scattering results, in terms of the orientation and bonding for the alcohols and the thiol, are similar on rough and mirrored electrodes. This observation suggests that SERS probes the average surface molecules in these cases and not only those existing at chemically distinct surface sites. The utility of emersed electrode approaches for molecular characterization of the electrochemical interface is demonstrated for these systems. The interfacial molecular structure for these in situ organic species appears to be maintained upon emersion.
• Pemberton, J. E., & Sobocinski, R. L. (1989). Raman spectroscopy with helium-neon laser excitation and Charge-Coupled Device detection. Journal of the American Chemical Society, 111(2), 432-434.
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  Abstract: Raman spectroscopy with He-Ne laser excitation and charge-coupled device (CCD) detection has been demonstrated for liquid pyridine and solid anthracene samples. The high quantum efficiency and essentially noiseless operation of the CCD make it ideal for use with low-intensity lasers such as the He-Ne laser. The possible utility of this experimental scheme as an alternative to Fourier transform Raman spectroscopy is discussed. © 1989 American Chemical Society.
• Sims, T. D., Lee, P. A., Pemberton, J. E., & Armstrong, N. R. (1989). Comparison of Supramolecular Structure and Spectroscopic & Photoelectrochemical Properties of Tetravalent and Trivalent Metal Phthalocyanine Thin Films. Chemistry of Materials, 1, 26-34.
• Goodby, B. E., & Pemberton, J. E. (1988). XPS CHARACTERIZATION OF A COMMERCIAL Cu/ZnO/ Al//2O//3 CATALYST: EFFECTS OF OXIDATION, REDUCTION AND THE STEAM /REFORMATION OF METHANOL.. Applied Spectroscopy, 42(5), 754-760.
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  Abstract: X-ray photoelectron spectroscopy (XPS) is used to characterize the surface region of a commercial Cu/ZnO/Al//2O//3 (33/66/1 wt percent) catalyst. A systematic study of the effects of oxidation, reduction, and the steam reformation of methanol on the oxidative state of the Cu component is presented. The Zn XPS features show no changes due to the various treatments. Peak fitting procedures were developed to quantitate the Cu oxidation states on the basis of the XPS Cu 2P//3/////2 main and satellite features. After oxidation in pure O//2 at 300 degree C, all Cu exists as Cu** plus **2. The Cu/Zn ratio changes from 0. 28 to 0. 37 as a result of this oxidation, in comparison to the ratio in the catalyst as-received.
• Pemberton, J. E., Guy, A. L., Sobocinski, R. L., Tuschel, D. D., & Cross, N. A. (1988). Surface enhanced Raman scattering in electrochemical systems: The complex roles of surface roughness. Applied Surface Science, 32(1-2), 33-56.
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  Abstract: A series of experiments designed to elucidate the presence and properties of large-scale and atomic-scale roughness produced on Ag electrodes with electrochemical oxidation-reduction cycle (ORC) pretreatments are presented. This report reviews surface enhanced Raman scattering (SERS) and scanning electron microscopic (SEM) characterization of Ag electrodes roughened with controlled-rate ORCs, and presents new results for the laser-induced thermal decay of SERS as a probe of Ag surface active sites and differential reflectance spectroscopy of electrochemically roughened Ag electrodes. These results are interpreted in terms of the presence and properties of both large-scale and atomic-scale roughness on these surfaces. © 1988.
• Sobocinski, R. L., & Pemberton, J. E. (1988). Laser-induced thermal decay of pyridine and chloride surface-enhanced Raman scattering as a probe of silver surface-active sites. Langmuir, 4(4), 836-845.
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  Abstract: The activation parameters for the temperature-dependent irreversible loss of surface-enhanced Raman scattered (SERS) intensity from pyridine and chloride adsorbed at silver surfaces in an electrochemical environment have been determined. Laser-induced heating is used to promote a first-order surface reaction at these roughened silver electrodes and is introduced as a probe of the chemical nature of SERS-active sites. Accurate laser-induced surface temperatures must be known for these experiments and are calculated from spectroscopic data. It is found that the kinetic data follow Arrhenius behavior for both pyridine and chloride. The activation energies associated with the destruction of SERS-active sites at a surface roughened by an illuminated oxidation-reduction cycle (ORC) are 12.8 ± 3.2 and 27.7 ± 3.1 kcal/mol for pyridine at two different types of sites on the Ag surface. Similarly, values for coadsorbed chloride are found to be 11.1 ± 2.4 and 24.5 ± 3.8 kcal/mol. Experiments designed to elucidate the decay mechanism suggest that the laser-induced surface reaction involves desorption of pyridine and chloride from active sites allowing their incorporation into the Ag lattice. The observation of two activation energies in the same temperature region is interpreted in terms of SERS-active sites, which exist at a surface defect and on a terrace plane, respectively. This interpretation is based on the relative activation energies and preexponential factors. The activation parameters for pyridine and chloride desorption are also evaluated at a silver surface roughened by a nonilluminated ORC. An activation energy of 27.4 ± 1.9 kcal/mol is obtained for pyridine on these surfaces. This result suggests that a greater concentration of terrace plane SERS-active sites is present at a surface roughened by an illuminated ORC. © 1988 American Chemical Society.
• Tuschel, D. D., & Pemberton, J. E. (1988). EFFECTS OF LASER ILLUMINATION DURING CONTROLLED-RATE. Langmuir, 4(1), 58-62.
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  Abstract: A study of the effects of laser wavelength and power density during controlled-rate illuminated oxidation-reduction cycles (ORCs) of Ag electrodes on the surface-enhanced Raman scattering (SERS) intensity of the v(Ag-Cl) band is reported. SERS spectra were acquired with a constant excitation wavelength after illuminated ORCs to deconvolute the SERS excitation behavior from the ORC illumination effects. Enhancement of SERS intensities is greater for illumination in the blue and green wavelength regions than for illumination in the red wavelength region. This enhancement is selective for the illumination position on the Ag electrode during the ORC. These results suggest the enhancement results from a photoeffect analogous to latent image formation in silver halide photography.
• Coria-Garcia, J., Pemberton, J. E., & Sobocinski, R. L. (1987). SERS investigation of interfacial Pb(II) species in weakly acidic aqueous halide media. Journal of Electroanalytical Chemistry, 219(1-2), 291-309.
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  Abstract: Surface-enhanced Raman scattering (SERS) has been used to study surface adsorbates at Ag electrodes from weakly acidic Cl-1 and Br-1 solutions containing Pb(II). Spectra in the low-frequency region (< 300 cm-1) indicate the presence of hydroxolead(II) complexes ionically bonded to specifically absorbed halide ions at the Ag surface. Studies of the effect of pH and halide ion concentration on the measured SERS intensities suggest that the surface precipitate has a composition in the ratio Pb(II):OH-1:X-1 of 1:1:1. The underpotential deposition of Pb quenches the intensities of these bands at different rates as a function of Pb coverage. These results suggest contributions from chemical effects in SERS of these systems. Additionally, a band at 110 cm-1 grows in intensity as the first Pb monolayer is deposited on the Ag surface in Cl-1 media. This vibration is tentatively assigned as Pb-Pb stretch. © 1987.
• Cross, N. A., & Pemberton, J. E. (1987). Surface enhanced Raman scattering of pyridine on Ag electrodes formed with controlled-rate oxidation-reduction cycles. Journal of Electroanalytical Chemistry, 217(1), 93-100.
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  Abstract: A study has been performed in which the SERS intensity of the pyridine ring breathing vibration at 1008 cm-1 at Ag electrodes is found to be dependent upon both the large scale and atomic scale roughness of the electrode surface. The controlled surface morphology is generated by a double potential step ORC technique. Scanning electron microscopy of these surfaces reveals varying large scale surface morphologies that are dependent upon ORC rate. A correlation between SERS intensity and large scale surface morphology is interpreted in terms of significant contributions from electromagnetic effects in electrochemical SERS. The correlation between SERS intensity and this surface morphology is found to be independent of the presence of atomic scale roughness. The results presented here confirm and extend the results of previous investigations of the morphology of SERS-active surfaces. © 1987.
• Guy, A. L., & Pemberton, J. E. (1987). CONTRIBUTIONS OF ATOMIC-SCALE ROUGHNESS AND ADSORBATE COVERAGE TO THE QUENCHING OF THE SERS RESPONSE AT LEAD-MODIFIED SILVER ELECTRODES.. Langmuir, 3(1), 125-132.
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  Abstract: This report details a series of experiments and calculations designed to provide a more complete analysis of the factors which may contribute to the quenching of the SERS response at Pb-modified Ag electrodes. SERS intensity-Pb coverage profiles are presented for the pyridine ring-breathing vibration after the majority of atomic-scale roughness features are destroyed by Pb monolayer deposition. Comparison of the morphology of the intensity-coverage profiles obtained during and after the loss of atomic-scale roughness indicates that loss of the majority of atomic-scale roughness during Pb deposition cannot fully account for the observed quenching of the SERS response. The SERS response of 3, 6-dihydroxypyridazine (DHPZN) is examined in order to evaluate the impact of adsorbate coverage on the observed quenching behavior. X-ray photoelectron spectroscopic studies of DHPZN adsorbed at Ag and Pb-modified Ag electrodes indicate that changes in the adsorbate surface coverage during Pb deposition do not contribute significantly to the quenching of the SERS response.
• Guy, A. L., & Pemberton, J. E. (1987). INTERPRETATION OF SERS INTENSITY-LEAD COVERAGE PROFILES FOR PYRIDINE AND CHLORIDE ION IN TERMS OF ELECTROMAGNETIC ENHANCEMENT AND CHARGE-TRANSFER EXCITATION.. Langmuir, 3(5), 777-785.
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  Abstract: The excitation behavior of the quenching of SERS for pyridine and Cl** minus at Ag electrodes in the presence of monolayer and submonolayer amounts of underpotentially deposited Pb is presented in this report. Intensity-coverage profiles are presented for the ring-breathing mode of pyridine with laser excitation. Electromagnetic contributions to the quenching behavior are evaluated by comparison of the experimental quenching profiles with theoretical profiles. Theoretical profiles are calculated from a model which predicts electromagnetic enhancement at overlayer-covered metal ellipsoids. The experimental and theoretical profiles are in poor agreement, especially for excitation in the red-wavelength region. A chemical model based on photoassisted charge transfer is proposed to account for the experimental behavior at other excitation wavelengths.
• Kellogg, D. S., & Pemberton, J. E. (1987). Effects of solution conditions on the surface-enhanced Raman scattering of cyanide species at Ag electrodes. Journal of Physical Chemistry, 91(5), 1120-1126.
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  Abstract: The effect of solution pH and supporting electrolyte anion on the SERS behavior of cyanide species adsorbed at Ag electrodes is described. Signals for the v(CN) are observed in both acidic (pH 2) and basic (pH 11) media in ClO4-, Cl-, and SO42- supporting electrolytes. The frequency and intensity of the v(CN) band are a function of electrode potential in all media. The potential at which the SERS signal reaches a maximum intensity is slightly dependent on the anion of the supporting electrolyte in basic media, but is a strong function of the anion in acidic media. In acid solution, HCN is adsorbed. Two unresolved bands occur in the v(CN) region in acidic media and several possible assignments are proposed. The assignment that best explains all of the experimental data involves both end-bonded and side-bonded HCN. The effect of supporting electrolyte anion on the SERS response is explained in terms of the relative abilities of these anions to influence the self-association of HCN in the interface. © 1987 American Chemical Society.
• Kellogg, D. S., & Pemberton, J. E. (1987). Surface-enhanced Raman scattering of HCN at Pb-modified Ag surfaces. Journal of Physical Chemistry, 91(5), 1126-1130.
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  Abstract: The surface-enhanced Raman scattering (SERS) behavior of HCN at polycrystalline Ag electrodes modified by monolayer and submonolayer amounts of underpotentially deposited Pb is presented. Changes in SERS intensity as a function of Pb coverage are interpreted in terms of preferential displacement of HCN from active sites by deposited Pb. By comparison with previous results obtained with pyridine and Cl- as adsorbates in similar experiments, these data suggest that both large-scale and atomic-scale roughness features contribute significantly to the SERS intensities measured in these systems. © 1987 American Chemical Society.
• Pemberton, J. E., & Girand, M. M. (1987). Electrochemical and SEM characterization of Ag electrodes roughened by potential sweep and potential step processes in aqueous chloride and chloride + pyridine media. Journal of Electroanalytical Chemistry, 217(1), 79-92.
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  Abstract: The effect of solution pH and the presence of pyridine on the redox behavior of Ag electrodes in aqueous chloride media is investigated. Scanning electron microscopy is used to evaluate differences in surface morphology of Ag electrodes subjected to electrochemical oxidation and oxidation-reduction processes in 0.1 M KCl and 0.1 M KCl + 0.05 M pyridine media at pH values of 2, 7, and 12. Potential sweep and potential step methods are used to effect the electrochemical oxidation and oxidation-reduction events. Comparisons are made between the resulting surface morphologies on the submicroscopic level for Ag surfaces roughened in these two ways. The redox chemistry of the oxidation and reduction processes is interpreted in terms of the different species capable of interacting with the Ag electrode surface and Ag+ species generated during oxidation in each medium. Surface adsorbates proposed to be important include chloride ions and pyridine. The relative importance of these species in terms of their ability to influence the redox chemistry of the Ag electrodes is seen to be a sensitive function of solution pH. © 1987.
• Pemberton, J. E., Coria-Garcia, J. C., & Hoff, R. L. (1987). EFFECT OF UNDERPOTENTIALLY DEPOSITED LEAD ON THE SERS OF CHLORIDE, BROMIDE, AND THIOCYANATE ADSORBED AT SILVER ELECTRODES: EVIDENCE FOR CHEMICAL CONTRIBUTIONS TO SERS.. Langmuir, 3(2), 150-159.
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  Abstract: A study of the effect of underpotentially deposited Pb on the SERS of Cl** minus , Br** minus , and SCN** minus adsorbed at Ag electrodes is presented in this report. The quenching behavior of the SERS of these adsorbates by the deposited Pb is different for each adsorbate. The SERS of SCN** minus is quenched rapidly by very small amounts of underpotentially deposited Pb, while the quenching for Br** minus and Cl** minus is less drastic. These results are interpreted in terms of a charge-transfer model for SERS that is sensitive to the changes in work function at microscopic sites upon Pb deposition.
• Helms, J. H., W., L., Hatfield, W. E., Harris, D. L., Jayaraj, K., Toney, G. E., Gold, A., Mewborn, T. D., & Pemberton, J. R. (1986). Effect of meso substituents on exchange-coupling interactions in μ-oxo iron(III) porphyrin dimers. Inorganic Chemistry, 25(14), 2334-2337.
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  Abstract: The μ-oxo iron(III) porphyrin dimers [(TPP)Fe]2O, [(TPP(4-OCH3))Fe]2O, [(TPP(4-CF3))Fe]2O, and [(TPP(F5))Fe]2O (where TPP is meso-tetraphenylporphyrin, TPP(4-OCH3) is meso-tetrakis(4-methoxyphenyl)porphyrin, TPP(4-CF3) is meso-tetrakis(4-(trifluoromethyl)phenyl)porphyrin, and TPP(F5) is meso-tetrakis(pentafluorophenyl)porphyrin) have been studied to determine the effect of peripheral substituents on the porphyrin rings on properties of the molecules. Variable-temperature magnetic susceptibility studies on solid samples yielded the following exchange-coupling constants for the antiferromagnetically coupled iron(III) ions: -146.8 cm-1, [(TPP(4-OCH3))Fe]2O; -135.7 cm-1, [(TPP)Fe]2O; -136.4 cm-1, [(TPP(4-CF3))Fe]2O; -146.9 cm-1, [(TPP(F5))Fe]2O. Variable-temperature 13C NMR studies of dichloromethane solutions yield exchange-coupling constants of -150 cm-1 for [(TPP(4-OCH3))Fe]2O, -145 cm-1 for [(TPP)Fe]2O, and -129 cm-1 for [(TPP(F5))Fe]2O. Raman spectra were collected in the region of the energy of the outer-ring stretching modes found at approximately 1560 cm-1. The position of this band is empirically related to the porphyrin core size, and the data indicate that the porphyrin center-pyrrole nitrogen (Ct-N) distances increase in the order [(TPP(F5))Fe]2O < [(TPP(4-CF3))Fe]2O < [(TPP)Fe]2O < [(TPP(4-OCH3))Fe]2O. The data support the hypothesis that the porphyrin ring core size increases as the electron-releasing capability of the peripheral substituent increases. For the para-substituted complexes, increasing core size correlates with stronger axial binding, reflected in stronger antiferromagnetic coupling. The anomalous behavior of [(TPP(F5))Fe]2O may result from distortions caused by steic interactions of the o-fluorines. © 1986 American Chemical Society.
• Tuschel, D. D., Pemberton, J. E., & Cook, J. E. (1986). SERS AND SEM OF ROUGHENED SILVER ELECTRODE SURFACES FORMED BY CONTROLLED OXIDATION-REDUCTION IN AQUEOUS CHLORIDE MEDIA.. Langmuir, 2(4), 380-388.
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  Abstract: The surface-enhanced Raman scattering (SERS) intensity of specifically adsorbed Cl** minus ions at Ag electrodes whose surface morphologies vary dramatically has been investigated. Reasonable control of the Ag electrode surface morphology is afforded by the controlled electrochemical rate of oxidation and reduction of the Ag surface prior to SERS experiments. Scanning electron microscopy is used to determine surface morphology on these electrodes of varying roughness. It is found that the SERS intensity increases as the diameter of the surface roughness features decreases and the two-dimensional surface concentration of roughness features increases. These observations are in general agreement with theoretical predictions based on an electromagnetic enhancement model for SERS.
• Guy, A. L., & Pemberton, J. E. (1985). TIME DEPENDENCE OF SURFACE ENHANCED RAMAN SCATTERING AT SILVER IN THE PRESENCE OF UNDERPOTENTIALLY DEPOSITED LEAD AND ITS IMPLICATIONS FOR THE ROLES OF SURFACE ROUGHNESS.. Langmuir, 1(4), 518-525.
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  Abstract: The recovery of the surface enhanced Raman scattering response for pyridine and Cl** minus adsorbed to roughened polycrystalline Ag substrates upon controlled deposition and quantitative stripping of underpotentially deposited Pb is presented. Recovery data are presented for both adsorbate vibrational features as a function of Pb coverage between 0. 0 and 1. 4 monolayers. The time dependence of the recovery behavior at potentials corresponding to 0. 2, 0. 5, and 1. 0 fractional Pb monolayer is also presented. The onset of SERS irreversibility is correlated with current-time transients for Pb overlayer formation.
• Guy, A. L., Bergami, B., & Pemberton, J. E. (1985). The effect of underpotentially deposited Pb on the surface enhanced Raman scattering ability of polycrystalline Ag. Surface Science, 150(1), 226-244.
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  Abstract: The effect of submonolayer and monolayer amounts of Pb deposited at underpotential on a polycrystalline Ag electrode surface on the surface enhanced Raman scattering behavior of pyridine and Cl- adsorbates is presented. Surfaces covered by greater than 70% of a Pb monolayer do not support significant surface enhancement. The changes observed in SERS intensity as a function of fractional Pb coverage are interpreted in terms of changes in surface electronic properties and changes in adsorbate coverage. Evidence for changes in the structure of the Pb overlayer is also presented. Investigation of the reversibility of the SERS behavior after deposition and quantitative stripping of varying amounts of Pb provides information on the roles played by various sizes of surface roughness in SERS. These data suggest that both large scale and atomic scale roughness contribute to the SERS intensities measured in these systems. © 1985.
• Pemberton, J. E. (1985). Surface enhanced Raman scattering at Ag electrodes in non-aqueous pyridine solutions. Chemical Physics Letters, 115(3), 321-327.
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  Abstract: The surface enhanced Raman scattering (SERS) of interfacial pyridine and Br- species at Ag electrodes from neat pyridine solutions containing tetra-n-butylammonium bromide is presented. The potential dependence of the SERS peak frequencies, bandwidths, and relative intensities is reported and interpreted in terms of pyridine reorientation in the double layer. A band at 221 cm-1 is observed at certain potentials and is assigned to the AgN stretch for Ag surface pyridine species. © 1985.
• Pemberton, J. E. (1984). INVESTIGATION OF THE ROLE OF SURFACE ELECTRONIC STRUCTURE IN SURFACE ENHANCED RAMAN SCATTERING IN ELECTROCHEMICAL SYSTEMS.. Extended Abstracts, Meeting - International Society of Electrochemistry, 451-453.
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  Abstract: Two avenues of research are currently under pursuit in an attempt to understand the role of surface electronic structure in SERS. The first involves the investigation of SERS activity at a series of mixed-metal surfaces fabricated by the electrochemical deposition of thin films of foreign metals onto substrate electrode surfaces. SERS intensities for adsorbates are measured as a function of film coverage and are related to the electronic properties of the surface and the structure of the metal overlayer. Results are presented for films of Pb on Ag surfaces, and films of Ag on Pt surfaces.
• Pemberton, J. E. (1984). SERS from thin Ag films electrochemically deposited onto Pt electrodes. Journal of Electroanalytical Chemistry, 167(1-2), 317-323.
• Pemberton, J. E., & Buck, R. P. (1983). Dithizone adsorption at metal electrodes. 5. Voltammetric and surface raman spectroelectrochemical investigation at a gold electrode. Journal of Physical Chemistry, 87(17), 3336-3343.
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  Abstract: Cyclic voltammetric and surface Raman spectroelectrochemical behavior of the anion of dithizone (diphenylthiocarbazone), HDz-, has been characterized at a Au electrode in aqueous alkaline media. The cyclic voltammetric results suggest that HDz- interacts with the Au electrode surface. The surface Raman spectroelectrochemical data are consistent with weak adsorption of HDz- at the Au surface. At potentials negative of 0 V, this adsorption appears to be weak relative to the previously noted adsorption of HDz- at Ag and Cu electrode surfaces. At potentials anodic of 0 V, oxidation of HDz- to the corresponding disulfide occurs. This disulfide adsorbs at the Au surface in multilayer quantities. The effect of solubility on the extent of adsorption was also investigated. The surface Raman data indicate that adsorption of HDz- is greater from pH 10 solution than from pH 12 solution. The adsorbed HDz- is postulated to reside in the outer Helmholtz plane in which it is still solvated, based on a comparison of the adsorbed HDz- spectra and a solution HDz- spectrum. This is in contrast to the behavior observed previously at Ag and Cu wherein the HDz- is thought to be contact adsorbed. © 1983 American Chemical Society.
• Pemberton, J. E. (1982). Quantitation of Adsorption Parameters and Adsorption Rates for Dithizone Anion Adsorption at Ag Using Surface Enhanced and Resonance Enhanced Raman Spectroscopy. Journal of the Electrochemical Society, 129, 21C.
• Pemberton, J. E., & Buck, R. P. (1982). Dithizone adsorption at metal electodes. Electrochemical characterization of dithizone anion at a silver electrode. Journal of Electroanalytical Chemistry, 132(C), 291-309.
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  Abstract: The redox behavior of the anion of diphenylthiocarbazone (dithizone) has been investigated at a silver electrode in alkaline media. The dithizone anion is reduced at the azo group at silver, but the observed voltammetric wave is split into surface and bulk components due to the adsorption of the anion at the silver surface. The product of this electrode reaction, the correponding hydrazo species, is also adsorbed at silver surface, but to a lesser extent. The cathodic processes for the dithizone anion reduction are complicated in alkaline solutions prepared with alkali hydroxides by the electrodeposition of alkali metals onto the silver surface and the subsequent formation of alkali metal-silver intermetallic compounds. The dithizone anion can also be oxidized at silver to form the corresponding disulfide compound. This disulfide, which is insoluble in the aqueous systems, adsorbs at the silver surface in multilayer quantities. This disulfide film passivates the silver electrode towards surface oxidation until potentials >ca. 400-500 mV (vs. Ag/AgCl) are reached. © 1982.
• Pemberton, J. E., & Buck, R. P. (1982). Dithizone adsorption at metal electrodes. 4. Voltammetric and surface Raman spectroelectrochemical investigation at a copper electrode. Journal of the American Chemical Society, 104(15), 4076-4084.
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  Abstract: Cyclic voltammetric and surface Raman spectroelectrochemical behavior of the anion of dithizone (diphenylthiocarbazone), HDz-, has been characterized at a Cu electrode in aqueous alkaline media. The cyclic voltammetry suggests very strong interaction of HDz- with the Cu surface. In the presence of HDz-, significant oxidation of the Cu surface does not take place until potentials greater than 0.2-0.3 V are reached. The surface Raman spectroelectrochemical data are consistent with strong adsorption of HDz- at the Cu surface at potentials negative of the oxidation potential. Very little control of surface HDz- population can be realized through alteration of the potential. This is in contrast to the previous behavior observed at Ag. The surface species observed at potentials more positive than the oxidation potential of HDz- is the disulfide. The effect of solubility on the extent of adsorption was also investigated. The surface Raman data indicate that adsorption of HDz- in pH 10 solution is significantly greater than that in pH 12 solution in which HDz- is more soluble. On the basis of the similarity of the surface spectra obtained and the spectrum of copper(II) dithizonate, an approximate orientation of HDz- at the Cu/solution interface is proposed. © 1982 American Chemical Society.
• Pemberton, J. E., & Buck, R. P. (1982). Dithizone adsorption at metal electrodes. 7. Preliminary characterization of adsorption kinetics using surface raman spectroelectrochemistry at a rotating disk silver electrode. Journal of Electroanalytical Chemistry, 136(1), 201-208.
• Pemberton, J. E., & Buck, R. P. (1982). Raman Spectroscopic Investigation of the Acid-Base Forms of Dithizone. Journal of Raman Spectroscopy, 12, 76-81.
• Pemberton, J. E., & Buck, R. P. (1982). X-ray photoelectron spectroscopic investigation of dithizone anion adsorption at silver and copper electrodes. Analytical Chemistry, 54(8), 1355-1362.
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  Abstract: X-ray photoelectron spectroscopy (XPS) has been used to investigate the adsorption of dithizone anion (HDz-) on silver and copper electrode surfaces from pH 12 aqueous alkaline buffer solutions. The XPS data of adsorbed dithizone forms were acquired on electrodes whose potentials had been set at a range of potentials from -1.2 to +0.6 V (vs. Ag/AgCl) in solutions of HDz-. These spectra are presented along with those obtained from authentic samples of neutral dithizone, bis(1,5-dlphenylformazan-3-yl) disulfide, 2,3-diphenyl-2,3-dl hydrotetrazolium-5-thiolate, silver(I) dithizonate, and copper(II) dithizonate. The XPS data are interpreted with respect to the nature of the surface species found at the electrode surfaces at different potentials, and the XPS data are correlated with the surface Raman behavior described previously. © 1982 American Chemical Society.
• Pemberton, J. E., & Buck, R. P. (1981). Detection of low concentrations of a colored adsorbate at silver by surface-enhanced and resonance-enhanced Raman spectrometry. Analytical Chemistry, 53(14), 2263-2267.
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  Abstract: The surface-enhanced Raman scattering (SERS) and resonance Raman scattering (RRS) enhancement mechanisms have been exploited in obtaining surface Raman spectra from the adsorbed anion of dithizone (diphenylthiocarbazone) at a silver electrode surface at -0.20 V (vs. Ag/AgCl) in pH 12 aqueous alkaline buffer solution. SERS+RRS spectra with acceptable signal-to-noise ratios were acquired from solutions initially 10-2 M through 10-9 M in dithizone anion. The SERS+RRS-detected adsorption isotherm is presented. Calculations of surface population based on the suggested orientation of dithizone anion at the silver surface allow a minimum SERS enhancement factor of 2 × 103 to be estimated for this system. © 1981 American Chemical Society.
• Pemberton, J. E., & Buck, R. P. (1981). Dithizone adsorption at metal electrodes. 2. Raman spectroelectrochemical investigation of effect of applied potential at a silver electrode. Journal of Physical Chemistry, 85(3), 248-262.
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  Abstract: The technique of laser Raman spectroelectrochemistry has been applied to the study of the adsorption of the diphenylthiocarbazone (dithizone) anion and its redox forms at a silver electrode in aqueous alkaline media. Raman spectra of the adsorbed forms of the dithizone moiety obtained at 100-mV intervals from -1.20 to +1.00 V (vs. Ag/AgCl) are presented. Comparison of these surface spectra with spectra obtained for authentic samples of the anion, silver(I) dithizonate, and the two oxidation products (tetrazolium and disulfide compounds) confirm the identity of the surface species at the various applied potentials. The anion, which adsorbs at potentials positive to the potential of zero charge (pzc), is oxidized to the disulfide at potentials greater than 0.00 V, and this disulfide is the predominant species found on the surface in the potential range 0.10-1.00 V. Comparison of vibrational frequencies as a function of applied potential for adsorbed dithizone with authentic silver(I) dithizonate shows that the bonding of Ag to N and S is similar in the two cases. Orientation of surface dithizone can be described approximately. © 1981 American Chemical Society.
• Pemberton, J. E., & Buck, R. P. (1981). ROTATING DISK CELL FOR RAMAN SPECTROELECTROCHEMISTRY: INVESTIGATION OF AN ELECTRODE SURFACE SPECIES AND AN ELECTROGENERATED SOLUTION SPECIES.. Applied Spectroscopy, 35(6), 571-576.
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  Abstract: A Raman spectroelectrochemical cell has been developed which incorporates a rotating disk design. This cell has been shown to be useful for the Raman investigation of electrode surface species (spinning electrode) and electrogenerated solution species (static electrode). It has been used to characterize the Raman spectroelectrochemical behavior of photolabile dithizone anion adsorbed at silver and copper electrode surfaces. Use of this cell for the study of electrogenerated solution species was demonstrated by the resonance Raman characterization of the tetracyanoethylene anion radical electrogenerated with a cyclic potential step. Cell construction is described and its merits discussed.
• Bancroft, E. E., Pemberton, J. E., & Blount, H. N. (1980). Reactions of cation radicals of EE systems. 10. The influence of ion association on cation radical disproportionation. Journal of Physical Chemistry, 84(20), 2557-2560.
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  Abstract: Disproportionation equilibria of the cation radicals of 10-phenylphenothiazine, thianthrene, and 9,10-diphenylanthracene have been voltammetrically characterized in acetonitrile, butyronitrile, nitrobenzene, and methylene chloride containing hexafluorophosphate, tetrafluoroborate, and perchlorate supporting electrolytes. Disproportionation was observed to be significantly influenced by associative interactions between the oxidized forms of the substrates and the anions of the supporting electrolytes. Disproportionation was found to be favored by anions of greater ionic potential. This anion effect in associated systems was observed to be "leveled" by solvents of increased polarity. In the absence of ion association, disproportionation was found to be favored by more polar solvents. © 1980 American Chemical Society.
• Pemberton, J. E., McIntire, G. L., Blount, H. N., & Evans, J. F. (1979). Reactions of cation radicals of EE systems. 9. Kinetics and mechanism of the reaction of thianthrene cation radical with nitrate ion. Journal of Physical Chemistry, 83(21), 2696-2703.
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  Abstract: The stoichiometry and dynamics of the reaction of thianthrene cation radical with nitrate ion have been studied in acetonitrile, butyronitrile, nitromethane, nitrobenzene, and methylene chloride. In all cases, the reaction is found to yield thianthrene 5-oxide exclusively, with no detectable thianthrene being regenerated during the reaction. The observed rate law in all solvents studied was found to be second order in thianthrene cation radical and first order in nitrate ion. The mechanism proposed for this reaction is analogous to the half-regeneration pathway but differs in that a bridged intermediate comprised of two cation radicals and a nitrate ion decomposes to form two molecules of the oxide and NO+. The observed rate constants, corrected for association equilibria involving nitrate ion, exhibit a linear inverse dependence on Dimroth-Reichardt solvent polarity (ET) parameters, thereby suggesting formation of the bridged intermediate as the rate-determining step in the reaction. © 1979 American Chemical Society.
• Pemberton, J. E., Hawkridge, F. M., & Blount, H. N. (1977). Small Volume, High Performance Cell for Nonaqueous Spectroelectrochemistry. Analytical Chemistry, 46, 1646-1647.

Proceedings Publications

• Khosroabadi, A. A., Matz, D. L., Gangopadhyay, P., Pemberton, J. E., & Norwood, R. A. (2013, Fall). Interface Between C60 and Ag on Nanostructured Plasmonic Ag Gratings: A SERS Study. In International Society for Optics and Photonics, 8809, L1-L7.
• Bowles, S. E., Shim, I., Benkoski, J. J., Karim, A., Kowalewski, T., Schalnat, M. C., Davis, R. J., Pemberton, J. E., & Pyun, J. (2007, August). Magnetic Assembly of Functionalized Ferromagnetic Colloids as Templates for 1-D Ordered Mesostructures. In 234th ACS National Meeting, PMSE Preprints, 97, 204.
• Lebron-Paler, A., Pemberton, J. E., & Maier, R. M. (2005, August). Effect of Aqueous Subphase Metal Ion on the Structure of Rhamnolipid at the Air-Water Interface. In 229th National Meeting of the American Chemical Society, ENVR Extended Abstracts, 45, 129.
• Pasilis, S. P., & Pemberton, J. E. (2003, March). Speciation and Coordination Chemistry of Uranyl (VI)-Citrate Complexes in Aqueous Solution. In 224th National Meeting of the American Chemical Society, ENVR Extended Abstracts, 43, 613-619.
• Pemberton, J. E., & Hawkridge, A. M. (2003, March). “Metal-Organic Interfaces in Organic Light-Emitting Devices (OLEDs) Studied by Surface Raman Spectroscopy. In 224th National Meeting of the American Chemical Society, PMSE Preprints, 88, 516.
• Robertson, J. W., & Pemberton, J. E. (2000, Summer). Nanochannel Electrodes Fabricated on Silica-Passivated Metals Using Scanning Probe Lithography. In Electrochemical Society National Meeting, 35, 16-24.
• Pemberton, J. E., Taylor, C. E., Goodman, G. G., & Mrozek, P. (1996, Summer). Surface Enhanced Raman Scattering: A Continuum of Possibilities. In XVth International Conference on Raman Spectroscopy, 618-619.
• Phule, P. P., Risbud, S. H., & Pemberton, J. E. (1990, Summer). Structural Evolution of Chemically-Derived Barium Tetratitanate (BaTi4O9) Powders. In Ceramic Transactions, American Ceramic Society, 15, 41-49.
• Pemberton, J. E., & McCloskey, S. J. (1989, Summer). Surface Enhanced Fluorescence of Basic Fuchsin at Roughened Silver Electrodes. In SPIE, 1054, 113-121.
• Pemberton, J. E., & Kellogg, D. S. (1985, Fall). Investigation of the Ag Electrode/Solution Interface in Aqueous and Nonaqueous Electrochemical Systems with Surface Enhanced Raman Scattering. In International Conference on Lasers, 433-440.

Presentations

• Pemberton, J. E. (2017, Spring). Organic Semiconductor Interfaces in Optoelectronic Devices: Undesirable Chemistry Galore!. 253rd American Chemical Society National Meeting & Exposition. San Francisco, CA: American Chemical Society.
• Boxley, C. J., Pemberton, J. E., & Maier, R. M. (2016, Spring). Synthetic Platform Technology to Create Known and Novel Bioinspired Glycolipids. 107th AOCS Annual Meeting. Salt Lake City, UT: American Oil Chemists Society.
• Eismin, R. J., Palos Pacheco, R., Munusamy, E., Hogan, D. E., Maier, R. M., Polt, R. L., Schwartz, S. D., & Pemberton, J. E. (2016, Summer). Microenvironment of Monorhamnolipid Aggregates and their Synthetically Produced Diastereomers as a Function of Solution Conditions. 252nd American Chemical Society National Meeting & Exposition. Philadelphia, PA: American Chemical Society.
• Fathi, S. A., Maier, R. M., & Pemberton, J. E. (2016, Summer). Synthesis, characterization, and heavy metal binding properties of new sugar-based glycolipid surfactants. 252nd American Chemical Society National Meeting & Exposition. Philadelphia, PA: American Chemical Society.
• Fathi, S. A., levine, J. D., & Pemberton, J. E. (2016, Summer). A comparison of sugar-based decyl glycoside surfactants from rhamnose, glucose, xylose and arabinose. 252nd American Chemical Society National Meeting & Exposition. Philadelphia, PA: American Chemical Society.
• Kegel, L. L., Szabo, L., Polt, R. L., & Pemberton, J. E. (2016, Summer). Alkyl thioglycoside green surfactant properties: Effects of various disaccharide and monosaccharide headgroup and alkyl tail length. 252nd American Chemical Society National Meeting & Exposition. Philadelphia, PA: American Chemical Society.
• Lachance, Z. L., Christie, H. S., & Pemberton, J. E. (2016, Summer). Green and Sustainable Chemistry in Secondary Education. 252nd American Chemical Society National Meeting & Exposition. Philadelphia, PA: American Chemical Society.
• Palos Pacheco, R., Kegel, L. L., Coss, C. S., Polt, R. L., & Pemberton, J. E. (2016, Summer). Structure-function relationships of bio-inspired rhamnolipid surfactants. 252nd American Chemical Society National Meeting & Exposition. Philadelphia, PA: American Chemical Society.
• Palos Pacheco, R., Kegel, L. L., Gonzalez, R., Polt, R. L., & Pemberton, J. E. (2016, Summer). Exploitation of chitin as a renewable feedstock for the synthesis of cationic and amphoteric glucosaminoside surfactants and their characterization. 252nd American Chemical Society National Meeting & Exposition. Philadelphia, PA: American Chemical Society.
• Pemberton, J. E. (2016, December 2016). Interface Chemistry in Organic Semiconductor Optoelectronic Devices: Buried but Not Forgotten. Amy-Mellon Lecture, Purdue UniversityPurdue University.
• Pemberton, J. E. (2016, Fall, 2016). Interface Chemistry in Organic Semiconductor Optoelectronic Devices: Buried but Not Forgotten. Materials Science and Engineering Colloquium. Tucson, AZ: University of Arizona.
• Pemberton, J. E. (2016, Spring). Interface Chemistry at Metal/Organic Contacts Relevant in Photonic Devices: Buried but Not Forgotten. University of Illinois at Urbana-Champaign. Urbana, IL: University of Illinois.
• Pemberton, J. E. (2016, Summer). Interface Chemistry at Metal/Organic Contacts in Photonic Devices: Buried but Not Forgotten. 2016 International Symposium on Analytical Chemistry Frontiers & China-US Analytical Chemistry Workshop. Xiamen, Fujian, China: Xiamen University.
• Pemberton, J. E. (2016, Summer). Interface Chemistry at Metal/Organic Contacts in Photonic Devices: Buried but Not Forgotten. Xi'an Jiaotong University. Xi'an, China: Xi'an Jiaotong University.
• Pemberton, J. E. (2016, Winter). Interface Chemistry at Metal/Organic Contacts Relevant in Photonic Devices: Buried but Not Forgotten. University of Washington. Seattle, WA: Department of Chemistry.
• Pemberton, J. E., Polt, R. L., Schwartz, S. D., Maier, R. M., & Klimecki, W. (2016, Summer). Biosynthetic and Bio-inspired Glycolipid Surfactants: Properties, Biodegradability, and Toxicity. 20th Annual Green Chemistry & Engineering Conference. Portland, OR: American Chemical Society Green Chemistry Institute.
• Eismin, R. J., Palos-Pacheco, R., Coss, C. S., Polt, R. L., Maier, R. M., & Pemberton, J. E. (2015, Spring). Aggregation Characteristics of Rhamnolipid Biosurfactants and Their Synthetic Variants. 106th Annual Meeting of the American Oil Chemists Society. Orlando, FL: Americanb Oil Chemists Society.
• Eismin, R. J., Palos-Pacheco, R., Hogan, D. E., Polt, R., Maier, R. M., & Pemberton, J. E. (2015, Spring). Speciation Behavior of Transition and Rare Earth Metal Binding by Monorhamnolipids. 249th American Chemical Society National Meeting & Exposition. Denver, CO: American Chemical Society.
• Hogan, D. E., Pemberton, J. E., & Maier, R. M. (2015, Spring). Biosurfactants as a Tool for Metal Removal from Waste Effluents. 106th Annual Meeting of the American Oil Chemists Society. Orlando, FL: American Oil Chemists Society.
• Kegel, L. L., Szabo, L., Polt, R. L., & Pemberton, J. E. (2015, Spring). Properties of Novel Bio-inspired Glycolipid Surfactants: Tailoring Function by Disaccharide Headgroup and Alkyl Tail Length. 106th Annual Meeting of the American Oil Chemists Society. Orlando, FL: American Oil Chemists Society.
• Kegel, L. L., Szabo, L., Polt, R., & Pemberton, J. E. (2015, Spring). Properties of Novel Bioinspired Glycolipid Surfactants: Tailoring Function by Disaccharide Headgroup and Alkyl Tail Length. 249th American Chemical Society National Meeting & Exposition. Denver, CO: American Chemical Society.
• Pemberton, J. E. (2015, Fall). Understanding and Overcoming Unconscious Bias: Some Things Never Change….or Do They?. Program for the Advancement of Women Scientists Meeting (inaugural seminar). University of Arizona.
• Pemberton, J. E. (2015, Summer). NSMDS: Molecular Design, Synthesis and Characterization of Green Glycolipid Surfactants through the Network for Bio-inspired Surfactants (NeBiS). Environmental Protection Agency/National Science Foundation Networks for Characterizing Chemical Life Cycle (NCCLC) and Networks for Sustainable Molecular Design and Synthesis (NSMDS) 2015 Grantees Meeting. Washington, DC.
• Pemberton, J. E., Palos-Pacheco, R., & Polt, R. (2015, Spring). Overcoming Production Limitations of Biosynthesis and Tailoring Rhamnolipid Biosurfactant Properties through Chemical Synthesis. 249th American Chemical Society National Meeting & Exposition. Denver, CO: American Chemical Society.
• Pemberton, J. E., Palos-Pacheco, R., Coss, C. S., & Polt, R. L. (2015, Spring). Tailoring Rhamnolipid Biosurfactant Properties through Production by Chemical Synthesis. 106th Annual Meeting of the American Oil Chemists Society. Orlando, FL: A,erican Oil Chemists Society.
• Pemberton, J. E., Palos-Pacheco, R., Coss, C. S., Gonzalez, R., Szabo, L., Hogan, D. E., Tian, F., Maier, R. M., & Polt, R. L. (2015, Winter). Tailoring Rhamnolipid and Related Glycolipid Surfactant Properties through Sustainable Production by Green Chemical Synthesis. The International Chemical Congress of Pacific Basin Societies 2015 (PacifiChem). Honolulu, HI.
• Pemberton, J. E., Szabo, L., Hogan, D. E., Malm, S., Palos-Pacheco, R., Tian, F., Kegel, L. L., Fathi, A., Gonzalez, R., Eismin, R. J., Coss, C. S., Hanrahan, D. J., Hunjan, A., Robin, P., Maier, R. M., & Klimecki, W. (2015, Summer). Quantitative Structure-Activity Relationships for Predicting Toxicity and Biodegradability of Biosynthetic and Bio-inspired Glycolipid Surfactants. 250th American Chemical Society National Meeting & Exposition. Boston, MA.
• Pemberton, J. E., Wang, H., Cheng, L., & Saez, A. E. (2015, Winter). Flow Field Penetration into Thin Nanoporous Polymer Films under Laminar Flow by Förster Resonance Energy Transfer Coupled with Total Internal Reflectance Fluorescence Microscopy. The International Chemical Congress of Pacific Basin Societies 2015 (PacifiChem). Honolulu, HI.
• Pemberton, J. E. (2014, Fall). GlycoSurf: Eco-Friendly Bio-inspired Surfactants Based on Carbohydrates. Rincon Rotary of Tucson. Tucson, AZ.
• Pemberton, J. E. (2014, Spring). Interface Challenges in Organic Photovoltaic Devices. Ohio State University. Columbus, OH: Department of Chemistry.
• Pemberton, J. E. (2014, Summer). NSMDS: Molecular Design, Synthesis and Characterization of Green Glycolipid Surfactants through the Network for Bio-inspired Surfactants (NeBiS). Environmental Protection Agency/National Science Foundation Networks for Characterizing Chemical Life Cycle (NCCLC) and Networks for Sustainable Molecular Design and Synthesis (NSMDS) 2014 Grantees Meeting. Washington, DC.
• Pemberton, J. E. (2014, Wiinter). Eco-Friendly Bio-synthesized and Bio-inspired Surfactants: How Sweet It Is!. Swarthmore College. Swarthmore, PA: Department of Chemistry.
• Pemberton, J. E. (2014, Winter). Eco-Friendly Bio-synthesized and Bio-inspired Surfactants Based on Carbohydrates. University of Arizona College of Science Advisory Board Meeting. Tucson, AZ: University of Arizona.
• Amooali, A. K., Gangopadhyay, P., Matz, D. L., Pemberton, J. E., & Norwood, R. A. (2013, Summer). SERS Measurement Study on the Interface of Nanostructured Plasmonic Ag Gratings and Thin C60 Layer. SPIE Optics and Photonics 2013. San Diego, CA.
• Pemberton, J. E. (2013, Fall). Eco-Friendly Biosurfactants and Bio-inspired Surfactants Based on Carbohydrates. University of Arizona Department of Chemistry & Biochemistry Advisory Board Meeting. Tucson, AZ: Department of Chemistry & Biochemistry.
• Pemberton, J. E. (2013, Fall). Eco-Friendly Biosurfactants and Bio-inspired Surfactants Based on Carbohydrates. University of Arizona Department of Chemistry & Biochemistry Alumni Reunion Symposium. Tucson, AZ: Department of Chemistry & Biochemistry.
• Pemberton, J. E. (2013, Fall). What is Peer Review?. ACS On Campus. Tucson, AZ: American Chemical Society.
• Pemberton, J. E. (2013, Spring). Green Glycolipid Surfactants: Inspired by Nature, Implemented by Chemists. Student Members of the ACS. Tucson, AZ: Americanb Chemical Society.
• Pemberton, J. E. (2013, Winter). Solution and Surface Aggregation Behavior of Bio-synthesized and Bio-inspired Glycolipid Surfactants. National Institute of Standards and Technology. Gaithersburg, MD: National Institute of Standards and Technology.
• Pemberton, J. E., & Ginger, D. S. (2013, July). The Science Behind Molecular Interface Modifiers: From Molecular Structure to Solar Cell Performance. DOE EFRC PI Meeting. Washington, DC: Department of Energy.
• Pemberton, J. E., & Mudalige, A. (2013, March). A New Take on an Old Concept: Electrochemical Interface Studies by the Technique ‘Formerly Known As’ Emersion. Pittsburgh Conference on Analytical Chemistry and Applied Spectroscopy. Philadelphia, PA.
• Pemberton, J. E., Matz, D. L., Sojoudi, H., & Graham, S. (2013, April). Interfaces of Single Layer Graphene with Low Work Function Metals. 2013 Materials Research Society Spring Meeting. San Francisco, CA.
• Pemberton, J. E., Mudalige, A., & Macech, P. (2013, April). Investigation of Silica-Water Interfaces using Forced Dewetting Coupled with Optical Spectroscopies. 245th American Chemical Society National Meeting & Exposition. New Orleans, LA.
• Shaw, S. K., Mudalige, A., & Pemberton, J. E. (2013, April). Thin surface films of water on hydrophilic and hydrophobic substrates: Changes in film behavior and H-bonding character studied by optical spectroscopies. 245th American Chemical Society National Meeting & Exposition. New Orleans, LA.
• Soemo, A. R., Maier, R. M., & Pemberton, J. E. (2013, April). Effect of Monorhamnolipid on the Dispersion Properties of Zinc Oxide Nanoparticles in Aqueous Solutions. 245th American Chemical Society National Meeting & Exposition. New Orleans, LA.
• Soemo, A. R., Maier, R. M., Camenisch, T., & Pemberton, J. E. (2013, April). Hydrogel Platform for Mitigation of Mining Tailings Dust. 245th American Chemical Society National Meeting & Exposition. New Orleans, LA.
• Pemberton, J. E. (2012, Spring). Interface Challenges in Organic Photovoltaic Devices. Colorado State University. Fort Collins, CO: Department of Chemistry.
• Pemberton, J. E. (2012, Spring). Interface Challenges in Organic Photovoltaic Devices. University of Colorado at Boulder. Boulder, CO: JILA.
• Pemberton, J. E. (2012, Winter). Interface Challenges in Organic Photovoltaic Devices. University of Notre Dame. South Bend, IN: Department of Chemistry.

Poster Presentations

• Pemberton, J. E. (2017, Spring). Degradation of Organic Semiconductors Part II. Pathways from Device Fabrications to Extended Ambient Exposure. 2017 Materials Research Society Spring Meeting and Exposition. Phoenix, AZ: Materials Research Society.
• Pemberton, J. E. (2017, Spring). Organic "Push-Pull" Semiconductors - Illumination on Degradation. 2017 Materials Research Society Spring Meeting and Exposition. Phoenix, AZ: Materials Research Society.
• Hanrahan, D., Palos-Pacheco, R., Szabo, L., Kegel, L., Pemberton, J. E., & Polt, R. (2016, March). Catalytically Promoted Glycosylation for the Synthesis of O- and S-linked Glycolipids. 251st American Chemical Society National Meeting & Exposition. San Diego, CA: American Chemical Society.
• Lachance, Z. L., Christie, H. S., & Pemberton, J. E. (2016, Summer). Green and Sustainable Chemistry in Secondary Education. 2016 Biennial Conference on Chemical Education (BCCE). Greeley, CO: BCCE.
• Gonzalez, R., Coss, C. S., Palo-s-Pacheco, R., Polt, R., & Pemberton, J. E. (2015, Spring). Synthesis of Glucosamine-Based Single Chain Nonionic and Cationic Surfactants. 249th American Chemical Society National Meeting & Exposition. Denver, CO: American Chemical Society.
• Hanrahan, D. J., Palos-Pacheco, R., Jones, E. M., Szabo, L., Kegel, L. L., Maier, R. M., Pemberton, J. E., & Polt, R. L. (2015, Spring). Synthesis and Structure-Function Relationships of Glycolipid Surfactants. LIPID MAPS Annual Meeting 2015. La Jolla, CA.
• Hogan, D. E., Palos-Pacheco, R., Polt, R. L., Pemberton, J. E., & Maier, R. M. (2015, Spring). Biosurfactants as a Tool for Metal Removal from Waste Effluents. 249th American Chemical Society National Meeting & Exposition. Denver, CO.
• Tian, F., Hogan, D. E., Pemberton, J. E., & Maier, R. M. (2015, Spring). Biodegradation and Toxicity of Synthetic and Natural Monorhamnolipids. 106th Annual Meeting of the American Oil Chemists Society. Orlando, FL: American Oil Chemists Society.
• Eismin, R. J., Coss, C. S., Palos-Pacheco, R., Maier, R. M., Polt, R., & Pemberton, J. E. (2014, Spring). Aggregation Characteristics of Rhamnolipid Biosurfactants and Several Synthetic Variants. 247th American Chemical Society National Meeting & Exposition. Dallas, TX.
• Garcia, I., Palos-Pacheco, R., Coss, C. S., Polt, R., & Pemberton, J. E. (2014, Spring). Greening the Synthesis of β-Keto Esters and β-Hydroxy Esters for Rhamnolipid Production. Undergraduate Poster Fair, Department of Chemistry and Biochemistry. Tucson, AZ: University of Arizona.
• Gonzalez, R., Coss, C. S., & Pemberton, J. E. (2014, Spring). Sustainable Surfactants from Renewable Resources. Undergraduate Poster Fair, Department of Chemistry and Biochemistry. Tucson, AZ: University of Arizona.
• Hogan, D. E., Pemberton, J. E., & Maier, R. M. (2014, Spring). Recovery of Critical Materials from Wastestreams using Biosurfactants. SWESx Symposium, University of Arizona EarthWeek Conference. Tucson, AZ: University of Arizona.
• Palos-Pacheco, R., Coss, C. S., Wang, H., & Pemberton, J. E. (2014, Spring). Structure-function Relationships of Bio-inspired Rhamnolipid Surfactants. 247th American Chemical Society National Meeting & Exposition. Dallas, TX.
• Palos-Pacheco, R., Coss, C. S., Wang, H., Polt, R. L., & Pemberton, J. E. (2014, March). Structure-function relationships of bio-inspired rhamnolipid surfactants. 247th National Meeting of the ACS. Dallas, TX: American Chemical Society.
• Palos-Pacheco, R., Coss, C. S., Wang, H., Polt, R., & Pemberton, J. E. (2014, Summer). Structure-function Relationships of Bio-inspired Rhamnolipid Surfactants. American Chemical Society Green Chemistry & Engineering Workshop. Washington, DC.
• Sang, L., Matz, D. L., Pemberton, J. E., Gliboff, M., Knesting, K., Ginger, D., Sigdel, A., Berry, J., Giordano, A., Marder, S., Li, H., & Bredas, J. (2014, Spring). Orientation and Reaction Chemistry of Phosphonic Acid-modified Indium-Zinc Oxide Surfaces in Organic Photovoltaic Devices. 247th American Chemical Society National Meeting & Exposition. Dallas, TX.
• Wang, H., & Pemberton, J. E. (2014, Spring). FRET Analysis of Mass Transport Behavior through Thin Polymer Films under Laminar Flow. 247th American Chemical Society National Meeting & Exposition. Dallas, TX.
• Armstrong, N. R., Pemberton, J. E., Bredas, J., Kahn, A., Ginger, D. S., Saavedra, S. S., Monti, O. L., Marder, S. R., McGrath, D. V., Nordlund, D., Berry, J. J., Olson, D. C., Ginley, D. S., Kippelen, B., Ratcliff, E. L., & Graham, S. (2013, July). An Integrated View of Critical Charge Harvesting Interfaces in Thin-Film Photovoltaics. DOE EFRC PI Meeting. Washington, DC: Department of Energy.
• Berry, J. J., Olson, D. C., Ratcliff, E. L., Cowan, S. R., Ndione, P., Widjonarko, N. E., Sigdel, A. K., Girodano, A. J., Ginley, D. S., Marder, S. R., Kahn, A., Schultz, P., Matz, D. L., & Pemberton, J. E. (2013, July). Design Guidelines for Contacts: Identifying Mechanisms at Organic/Oxide Interfaces that Control Energy Transfer. DOE EFRC PI Meeting. Washington, DC: Department of Energy.
• Coss, C. S., Palos-Pacheco, R., Pemberton, J. E., Hogan, D. E., & Maier, R. M. (2013, Summer). The Chemical Synthesis of Tailorable, Bio-Inspired Glycolipid Surfactants. ACS Summer School on Green Chemistry and Sustainable Energy. Golden, CO: American Chemical Society.

Others

• Pemberton, J. E., & Maier, R. M. (2015, August). Surfactants: building greener chemicals. NSF Science Nation. http://www.nsf.gov/news/special_reports/science_nation/surfactants.jsp