Spectral diffusion in liquids with fluctuating solvent responses: Dynamical heterogeneity and rate exchange

A recent theory for the time dependence of inhomogeneous line shapes is ext ended to account for fluctuations of the solvent response times tau in both space (heterogeneity) and time (rate exchange). Different simulation techn iques are outlined for solving the Ornstein-Uhlenbeck type spectral diffusi on in the situation expected for supercooled liquids. For intrinsically exp onential solvent dynamics, slow rate exchange (or static heterogeneity) has to be assumed in order to reproduce measurements of the Stokes-shift corre lation function C(t) and inhomogeneous linewidth sigma (t) simultaneously. (C) 2001 American Institute of Physics.