Abstract

Vibrational dephasing reflects the molecular dynamics of a liquid and the coupling of that motion to intramolecular coordinates. Both isotropic Raman line- shapes and time-resolved coherent Raman scattering have been extensively used to measure dephasing in liquids.^1,2 However, these experiments cannot directly determine whether the dephasing is caused by homogeneous or inhomogeneous processes, a distinction that is critical for interpretation of the data. Homogeneous broadening is caused by very rapid (typically <1 ps) solvent motions, and the resulting dephasing time is controlled by both the strength and the speed of the vibration-solvent interactions. Inhomogeneous broadening implies the existence of long- lived local structures in the liquid, and the resulting deplrasing time is a direct measure of the coupling between these structures and the vibration.

© 1992 Optical Society of America