Journal of Chemical Physics, Vol.109, No.5, 2038-2042, 1998
Depolarized light scattering in the isotropic phase of liquid crystals
The polarized and depolarized Rayleigh light scattering spectra for the isotropic phase of p-methoxybenzylidene-n-butylaniline (MBBA) and 4-cyano-4-penthylbiphenyl (5CB) were measured in order to investigate the coupling between translational and orientational modes of molecular motion. The Rayleigh dip was observed in depolarized light scattering spectra of isotropic phase of both liquid crystals in the wide temperature ranges. The Rayleigh dip spectrum was attributed to the coupling between orientational and translational mode of molecular motions in anisotropic molecules. Data analysis based on the Alms' theory (J. Chem. Phys. 67(12), 5779 (1977)) leads to the evaluation of the coupling parameter R. The temperature dependence of the coupling parameter of both liquid crystals near the phase transition point was discussed.