Tailoring of cholesteric plane spacing, dielectric relaxation and optical properties of high temperature chiral nematic phase by UV irradiation

Abstract

The effect of Ultra Violet (UV) irradiation on the high temperature chiral nematic (N*) mesophase has been investigated. The controlled UV exposure produced bending in rod shape molecules. The bending of molecules affects their long molecular axis; therefore, the relaxation mode associated with the rotation of molecules along the long molecular axis shifts toward the higher frequency. The UV irradiation also increases the cholesteric plane spacing of N*LC molecules. The a.c. conductivity of N*LC has been increased enormously after UV irradiation. The efficiency of opto-dielectric effect has also been evaluated with the variation of bias voltage in the present investigation.