Pore-Size-Dependent Orientational Dynamics of a Liquid Crystal Confined in a Porous Glass

Abstract

Time-resolved transient grating optical Kerr effect experiments were used to investigate the collective reorientational dynamics of pentylcyanobiphenyl embedded in the nanometer-length-scale pores of silica glasses. Measurements in the bulk pretransitional temperature range show a drastic decrease of the relaxation time of the order-parameter fluctuations compared to the bulk with a pronounced pore-size dependence. A Landau model based on independent pore segments can explain the pore-size dependence, but cannot satisfactorily reproduce the observed nonexponentiality of the decays.