Interaction induced phenomena in Raman spectra of mesogens

Abstract

We present the results of experimental studies of light scattering in the isotropic phase of two mesogens, p-n-pentyl-p′-cyanobiphenyl (5CB) and p-n-pentyl-(p′-cyanophenyl)-cyclohexane (5PCH) and in their solutions in CCl4, a globular molecules solvent. Integral intensities of various Raman bands and Rayleigh wing polarized spectra were studied. Dilution experiments have shown that in mesogen systems, due to molecular interactions, intensity of light scattering may be substantially (about 30%) reduced. Isotropic component of the scattered light is influenced by orientation-translational molecular correlations, while for anisotropic component pure orientational molecular correlations are also important. As a result, depolarization ratio in the condensed state may be substantially different from that for the isolated molecule and may vary through the mesomorphic phase transitions.