This research, part of the experimental Physical Chemistry Program, applies picosecond and femtosecond time resolved spectroscopic techniques to the study of solvation dynamics, electron transfer reactions, vibrational and orientational relaxation, and diffusion controlled reactions. These studies will elucidate how the interactions between dissolved molecules and their surroundings influence molecular relaxation and reactivity. The pathways of vibrational relaxation of medium-sized molecules in a variety of solvents will be investigated by taking advantage of improvements in tunability, sensitivity and time resolution of laser systems. The extent of inhomogeneous broadening in vibrational lineshapes will be examined by using a Raman echo technique in which a pair of pulses excite a coherent superposition of vibrational states. Such a system evolves until a second pulse pair rephases the vibrations. After a second delay the phase coherence is probed by Stokes scattering induced by a third laser pulse. The origin of nonexponential decays in charge transfer reactions will be studied. In particular, the role of a non-equilibrium initial state in strongly adiabatic electron transfer reactions will be explored.
