Influence of Solvent-Solute Interact#ins on Molecular Dynamics

本研究是实验物理化学计划的一部分，应用皮秒和飞秒时间分辨光谱技术来研究溶剂化动力学、电子转移反应、振动和取向弛豫以及扩散控制反应。这些研究将阐明溶解分子与其周围环境之间的相互作用如何影响分子的弛豫和反应性。利用激光系统在可调性、灵敏度和时间分辨率方面的改进，研究了中等大小分子在各种溶剂中的振动弛豫途径。振动线形的非均匀扩展的程度将通过使用拉曼回波技术来检查，其中一对脉冲激发振动态的相干叠加。这样的系统会不断发展，直到第二个脉冲对使振动重新相位。在第二次延迟后，用第三次激光脉冲诱导的斯托克斯散射探测相位相干性。将研究电荷转移反应中非指数衰减的起源。特别地，非平衡初始态在强绝热电子转移反应中的作用将被探讨。

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.