Raman and depolarized Rayleigh scattering in the liquid state: Reorientational motions and correlations in orientation for symmetric top molecules

Abstract

Reorientational motions perpendicular to the major axis of symmetric top molecules in the liquid state have been examined as a function of temperature by investigating isotropic and anisotropic Raman scattering vibrational band contours. These studies yield information about single molecule reorientation for the systems C6H6, C6D6, CH3CN, CD3CN, CH3I, DCCl3, and HCBr3. Depolarized Rayleigh scattering measurements on the same systems, also as a function of temperature, are combined with data on single particle reorientations to yield information about correlations in orientations between pairs of molecules. These correlations between molecules are found to be important for most symmetric top molecules in the liquid state and the temperature dependence of the Raman and Rayleigh band shapes and bandwidths suggest that hard core forces dominate the cooperative motions in the systems studied.