Hydrodynamic correlation functions in nematic liquid crystals. Propagating modes

Abstract

The spectral densities of nematic liquid crystals are calculated in the hydrodynamic limit with particular reference to those spectral densities that play a role in the Brillouin lines of the light scattering spectrum. It is found that the contribution of the mixed pressure-director fluctuations to the intensity of the Brillouin lines is comparable to that of the pure pressure fluctuations. Exploitation of this feature allows, in principle, the determination of the flow-director coupling constant from the angular dependence of the intensity of the Brillouin lines.