Raman Scattering from Nematic Liquid-Crystalline Azoxybenzenes

We have investigated the Raman spectra of four nematic members of the homologous series 4,4′-bis (alkoxy) azoxybenzene in the solid, nematic, and liquid phases for a spectral range of 10–1900 cm−1. These spectra show great similarity, as one would expect from the similarity of their molecular structure. A few Raman modes, particularly the intermolecular ones, exhibit quasidiscontinuous changes at the phase transitions. These changes are qualitatively interpreted as the result of modification of the intermolecular interaction induced by the phase transitions.