Liquid Cl2 dynamics studied by depolarized Raman and Rayleigh scattering

Abstract

Polarized and depolarized Raman and Rayleigh spectra of liquid chlorine have been measured along the coexistence curve from 184 to 238 K. Results are compared with predictions of current simple models for rotational diffusion and vibrational dephasing in liquids. In accord with recent investigations for polyatomic species, it has been found that the temperature dependence of the single particle reorientational time τsp is proportional to the viscosity/temperature ratio, η/T. Despite evidence for specific angle-dependent valencelike forces between Cl2 molecules, comparison of the observed τsp with that predicted by the hydrodynamic ’’slip’’ and ’’stick’’ models shows clearly that the former provides much better agreement with experiment. The temperature dependence of the vibrational dephasing time is controlled by motional narrowing. A number of caveats associated with the extraction of reliable information concerning collective reorientational motions from depolarized Rayleigh scattering are briefly discussed.