Raman studies of some cyanobiphenyl derivatives under pressure

We present the results of an experimental study of the Raman depolarization ratio for the cyano stretching mode in two mesogens, 5CB and 80CB, under v ariable temperature and pressure. In contrast to previous observations, the Raman results do not yield any indication of molecular association, even i n such an expectedly strongly associated liquid crystal as 80CB, which has a re-entrant nematic phase at elevated pressure. Possible explanations for this are discussed.