Studies of Molecular Triplet States

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In this project in the Experimental Physical Chemistry Program, R. Bruce Weisman of Rice University will use laser pump-probe techniques to investigate the rates at which triplet excited states of molecules undergo vibrational energy relaxation and redistribution, electronic energy transfer, and reaction. Systems to be studied include triplet pyrazine and methylpyrazine using the rare gases, CO, methane, ethane, water, and benzene as relaxers. These relaxers span a range of mass, polarizability, and polarity, and will provide information to help clarify mechanistic differences between triplet and ground state relaxation. Further studies include the triplet decay mechanisms and kinetics of fullerenes in various solvents and in aqueous micelles. The fullerenes have been shown to produce triplet excimers, and these studies will determine the equilibrium constant for excimer formation and its variation with solvent and temperature. Due to their unpaired electron spins, triplet state molecules often exhibit rates of reaction and relaxation which are entirely different from those of the ground electronic state. Professor Weisman's studies will enhance our understanding of these important chemical differences and will clarify the mechanisms involved in excimer formation and vibrational energy redistribution and relaxation.