Temperature Effect on the Depolarization Degree of the Raman Active Totally Symmetric Vibrations of some Benzene Derivatives Belonging to Point Groups D_(6h) and D_(3h)

摘要

The temperature effect on the depolarization degree of the Raman bands of the totally symmetric vibrations of some benzene derivatives belonging to point groups D_(6h) and D_(3h) was studied. In these molecules a direct field due to incident light gives rise to an intrinsic depolarization, and an indirect field causes by dipoles induced in the surrounding molecules by the incident light gives rise to depolarization due to intermolecular interactions. It was observed that although the depolarization degree increases with increasing temperature for all vibrational modes, the relationship between the temperature and depolarization degree is different, depending on the vibrational modes as well as the substituents. These observations are qualitatively explained by a change in the intermolecular interaction due to thermal fluctuations of the intermolecular distance caused by molecular vibrations.