Raman Scattering Study of Phase Biaxiality in a Thermotropic Bent-Core Nematic Liquid Crystal

Abstract

Polarized Raman spectroscopy was used to investigate the development of orientational order and the degree of phase biaxiality in a bent-core mesogenic system. The values of the uniaxial order parameters <P200> and <P400>, and biaxial order parameters <P220>, <P420>, and <P440>, and their evolution with temperature were determined. The temperature dependence of almost all order parameters reveals a second order transition from the uniaxial to biaxial nematic phase with <P220> increasing to ∼0.22 before a first order transition to the smectic-C phase, upon cooling.