Ordering Behavior and Linear Dichroism of Pure and Doped Liquid Crystals

In the present paper, C7 liquid crystals’ refractive indices have been measured throughout the nematic and isotropic phase, in order to determine the order parameter by using Vuks method and characterization of anisotropic behaviors. The temperature dependence of refractive indices, birefringence and order parameters in the anisotropic phase, has been investigated for this liquid crystal. Furthermore, the dichroic ratios of doped C7 by linear azo dye, obtained on the basis of polarized absorption measurements. Then, the orientational ordering of the doped liquid crystal is analyzed by determining the order parameters, in different dye concentrations. The ordering behavior of a doped liquid crystal mixture is studied. It is found that even in very low compositional percentage of the dyes, the obtained order parameters are strongly affected by increasing the dye concentration.

Refractive indices;Vuks method; dichroism; doped liquid crystal; polarized spectroscopy