Vanessa Margaret Huxter

Biography

My research is focused on the development of incisive optical experiments to explore previously intractable questions in systems ranging from solid-state materials to light harvesting pigment-protein complexes to small molecules. I have a substantial background in ultrafast spectroscopy and the application of these techniques to the study of energy and charge transfer, vibrational and spin dynamics, electronic coherence, multiexciton states and physical material properties among others.

I have used linear and non-linear spectroscopic techniques to study the material and optical properties of colloidal semiconductor nanocrystal and molecular systems, observing and analyzing energy dynamics in both singly and multiply excited nanocrystal ensembles and using optical measurements as a tool to determine their material properties. From my ultrafast measurements, a longstanding debate in the literature was resolved. This concerned optical properties of a class of bulk-like colloidal semiconductor nanocrystals that displayed ‘quantum confined’ type optical spectra. I also investigated dynamic electron correlation in molecular systems using a new double quantum coherence experimental technique. Using an anisotropy-type signal, I performed the first measurement of relaxation within the fine structure of CdSe nanocrystals. This measurement demonstrated a novel technique for disentangling spin dynamics using optical spectroscopy and directly led to an understanding of the effect of nanocrystal shape on the optical properties. By further developing this new spectroscopic technique, I was able to quantify previously obscured material properties of nanocrystals in solution. These measurements revealed the size-dependent modification of the elastic properties and related that to a change in surface energy. This was the first demonstration of the in-situ measurement of surface stain, which controls the growth kinetics in colloidal nanoparticle systems and is critical for nanocrystal design. Beyond experimental work, I developed a new theoretical expression for elasticity and surface strain in nanoparticles and wrote extensive modeling code to simulate and disentangle the origins of the observed nonlinear signals.

I have employed state-of-the-art two-dimensional electronic spectroscopic techniques (2DES) to study energy flow in solid-state systems. Currently, there are only a handful of groups in the world capable of these experiments that provide an unprecedented level of insight into electronic processes. I performed the first ultrafast experiment on negatively charged nitrogen vacancy centers in diamond (NVDs) using 2DES. These measurements provided a window into the complex coherent vibrational dynamics of NVDs, which are of interest due to their range of optical and material properties that make them attractive for quantum computing and processing applications. In these measurements I observed cooperative coherent vibrational dynamics and ultrafast energy transfer between a large, structured phonon side band and the triplet electronic state. I was able to characterize the complex vibrational bath of the defect, which is critical for associated applications including magnetometry, quantum information and processing, single photon emission and imaging. This measurement represents the first ultrafast probe of NVD material dynamics and also the first 2DES measurement of a freestanding, monolithic solid-state material. In order to perform this measurement, I developed a series of technological advancements that were implemented in the experimental design.

I have also built a new 2DES spectroscopy apparatus using modern pulse shaping techniques to study photosynthetic pigments and pigment-protein complexes. My colleagues and I were able to identify excitation overlaps and the contributions of multiple excitations in the Fenna-Matthews-Olsen photosynthetic pigment-protein complex using this novel apparatus. Using the 2DES experiment, a group of researchers and I investigated the properties of the orange carotenoid protein that has a photoprotective role in natural light harvesting in cyanobacteria. These measurements revealed the dynamics of photoswitching and deactivation pathways driven by vibrational dynamics. These results have important implications for both natural and artificial light harvesting strategies.

Degrees

• Ph.D. Physical Chemistry
• University of Toronto, Toronto, Ontario, Canada
• Optical and Material Properties of Colloidal Semiconductor Nanocrystals
• B.S. Chemistry
• McGill University, Montreal, Quebec, Canada
• Tandem Calibration Methodology: Dual Nebulizer Sample Introduction for ICP-MS

Awards

• Journal of Physical Chemistry Editorial Advisory Board Member
• Journal of Physical Chemistry, Spring 2017
• Faculty Member of the UA Institute for Energy Sciences
• UA Institute for Energy Sciences, Fall 2016
• University of Arizona Sloan Fellowship Nominee
• University of Arizona, Fall 2015 (Award Nominee)
• Scialog Collaborative Innovation Award
• Research Corporation for Science Advancement, Spring 2015
• Scialog Fellow: Molecules Come to Life
• Research Corporation for Science Advancement, Spring 2015
• University of Arizona Packard Fellowship Nominee
• University of Arizona, Spring 2015 (Award Nominee)
• Scialog Fellow: Solar Energy Conversion
• Research Corporation for Science Advancement, Fall 2014
• Ultrafast Phenomena Grant for Young Scientists
• Summer 2012