Coherence Length in the Isotropic Phase of a Room-Temperature Nematic Liquid Crystal

Abstract

The polarized (${I}_{\ensuremath{\parallel}}$) and depolarized (${I}_{\ensuremath{\perp}}$) scattered light intensity by fluctuations of the order parameter $Q$ near the isotropic-nematic phase transition of para-methoxybenzylidene para-$n$-butylaniline has been measured as a function of the scattering angle over a range of temperatures above the phase-transition temperature ${T}_{p}$ by means of two different incident wavelengths. Our results are in excellent agreement with the phenomenological theory of de Gennes. We also find the elastic constants ${L}_{1}\ensuremath{\gg}{L}_{2}$ while ${L}_{1}$ depends upon temperature.