Laser Control of Molecular Conformation as an Avenue for Practical Laser Chemistry

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Brooks Pate of the University of Virginia has been awarded a CAREER grant in the Experimental Physical Chemistry Program to initiate studies of laser control of molecular conformations for practical laser chemistry. The goal of these investigations is to selectively populate a single molecular conformational structure, resulting in an enhanced reaction rate along the desired pathway. In the two-laser experiment, molecules are first excited to an energy region where the vibrational states localized around the different conformational minima are coupled through intramolecular vibrational energy redistribution (IVR). Since the vibrational frequencies depend on conformation, a second (resonant) laser is then selected to stimulate emission to a lower state. This lower energy state lies below the onset energy for IVR, hence the final structure is localized around the one desired conformation. Little is known about the conformations that a vibrationally excited molecule can assume, yet reaction rates are strongly dependent on the conformational structure. These techniques will provide the first information of this type and hence may lead to truly ground-breaking results. The educational component of Prof. Pate's CAREER award will emphasize the development of a physical chemistry course along the lines of a `research training` course for those students interested in physical chemistry careers, better utilization of computers in the curriculum, e.g., symbolic math software for problem manipulations, and incorporation of modern research instrumentation in the laboratory courses.