Optical Study of Orientational Order Parameter in p-n-(Phenyl Benzylidene) -p-Alkyl and Alkyloxy Anilines

The refractive indices measurements are carried out using a modified spectrometer connected with wedge shaped cell and also the direct measurement of birefringence,δn obtained from Newton’s rings method with an indigenous setup for the liquid crystalline compoundsp-n-(phenyl benzylidene)-p-n-alkyl and alkyloxy anilines, PBnA and PBnOA compounds. The molecular polarizabilitiy anisotropy (α||- α⊥) is calculated for these compounds from different methods such as Lippincott δ-function model, molecular vibration method, Haller’s extrapolation method and scaling methods respectively. Further, the estimation of the molecular polarizabilities αeand αoare done from the isotropic Vuks and anisotropic Neugebauer models. The order parameter directly calculated from ∆n employing the method developed by Kuczynski is compared with the order parameter estimated from the different models using molecular polarizabilities.