Professor of Chemistry
Vice Provost for Academic & Student Affairs
Ph.D. University of California at Berkeley, 1992
Environmental Chemistry. In many chemical reactions of environmental interest, product formation dynamics are dependent on the phase (i.e., gas, solution, or solid) in which the chemistry occurs. We are particularly interested in the photochemistry of halogen-containing compounds, where the efficiency of halogen production is phase dependent. The goal of our research in this area is to develop a detailed understanding of this phase-dependent reactivity. To accomplish this goal, we employ a multidimensional experimental approach in which multiple time- and frequency-domain spectroscopic techniques (resonance Raman intensity analysis, time-resolved resonance Raman, time-resolved infrared and femtosecond pump-probe) are employed. The synergistic application of these spectroscopies allows for the study of chemical reactivity from the initial excited-state evolution to the appearance and relaxation of the ground-state products.
In collaboration with other research groups in the Center for Materials and Devices for Information Technology Research (CMDITR), we are developing novel optical materials for telecommunications and information processing. The recent development of promising organic photonic materials and special device architectures such as photonic bandgap lattices suggests that organic materials will play an important role in next generation of electro-optical (EO) switches. Our research in this area involves the characterization of these materials from single molecules up to molecular assemblies. Chromophore non-linear optical activity is characterized using frequency-agile hyper-Rayleigh spectroscopy. The intensity of hyper-Rayleigh scattering can be used to determine the non-linear optical performance of individual chromophores. Material characterization of chromophore-polymer composite materials is performed using linear and non-linear optical microscopy. These techniques combine 3-dimensional spatial resolution with single-molecule sensitivity allowing for detailed studies of chromophore-polymer composite materials. Our experimental results are directly compared to theory, with this synergistic approach providing for the development of more accurate theoretical methods thereby increasing the predictive ability of these techniques.
We are also collaborating with the Kahr group (New York University) in the study of molecules isolated in organic crystals. The Kahr group has demonstrated that when crystals of potassium hydrogen phthalate (KAP) are grown from aqueous solution in the presence of chromophores, the chromophores are incorporated into specific growth sectors of the crystal with the optical properties of the resulting crystal demonstrating that the chromophores are aligned. Our group performs single-molecule confocal microscopy studies of these materials. By measuring fluorescence dichroism, the orientation of each molecule can be determined and compared to bulk studies. In addition, we are studying the photophysical and emissive behavior in these composite systems. The blinking dynamics observed in many other single-molecule studies are dramatically reduced when the chromophores are incorporated into the crystal. In addition, those molecules that do blink demonstrate remarkably rich photophysical behavior. We are exploring the fundamental reasons behind this behavior using a variety of experimental and theoretical techniques.
J. C. Bolinger, T. Bixby, P. J. Reid. “Time-Resolved Infrared Studies of the Solvent Dependent Vibrational Relaxation Dynamics of Chlorine Dioxide.” J. Chem. Phys. 2005, 123, 084503.
C. C. Cooksey, P. J. Reid. “The Phase-Dependent Photochemical Reaction Dynamics of Halooxides and Nitrosyl Halide.” J. Photochem. Photobiol. 2004, 80, 368-400. (invited review article)
K. L. Wustholz, E. D. Bott, C. M Isborn, X. Li, B. Kahr, P. J. Reid. “Photophysics of Single-Molecules Oriented in Potassium Acid Phthalate Crystals.” J. Phys. Chem. C 2007, 111, 9146-9156.
Y. Liao, A. K. Y. Jen, B. H. Robinson, P. J. Reid, L. R. Dalton. “Linear and Nonlinear Optical Properties of a Macrocyclic Trichromophore Bundle with Parallel-Aligned Dipole Moments.” J. Phys. Chem. B 2006, 110, 5453-5438.
P. M. Wallace, D. R. B. Sluss, L. R. Dalton, B. H. Robinson, P. J. Reid. “Single-Molecule Microscopy Studies of Electric-Field Poling in Chromophore-Polymer Composite Materials.” J. Phys. Chem. B 2006, 110, 75-82.
K. Wustholz, B. Kahr, P. J. Reid. “Single-Molecule Orientational Studies of Dye-Doped Organic Crystals.” J. Phys. Chem. B 2005, 109, 16357-16362.