Liquid crystal dynamics in the isotropic phase

Abstract

The dynamics in the isotropic phase of the liquid crystal 1-isothiocyanato-(4-propylcyclohexyl) benzene (3-CHBT) are investigated from very short time (~1 ps) to very long time (>100 ns) as function of temperature. The data decay exponentially only on the longest time scale (>10 ns). The temperature dependence of the long time scale exponential decays is described well by the Landau-de Gennes theory of the randomization of pseudo-nematic domains that exist in the isotropic phase of liquid crystals near the isotropic to nematic phase transition. Over the full range of times, the data are fit with a model function that contains a short time power law. The power law exponent is temperature independent over a wide range of temperatures. Integration of the function gives the empirical polarizability-polarizability (orientational) correlation function. A preliminary theoretical treatment of collective motions yields a correlation function that indicates that the data can decay as a power law at short times. The power law component of the decay reflects intradomain dynamics.