Linear and non-linear electro-optical measurements in the study of polar liquid crystal phases

Abstract

ABSTRACTThe article shows that the recently presented technique based on the temperature dependence of the characteristic peak frequency (fext) of the real part of second harmonic electro-optic (EO) response can be complementary to the Debye type relaxation method, usually used to study the dynamical behaviour of liquid crystals (LCs). The most important advantages of this method are the sensitivity – no pretransitional effects observed, and simplicity – no fitting procedure necessary. The problem is illustrated with the experimental first and second harmonic EO spectra recorded for LC material with broad temperature range of the helical smectic subphases. The obtained values of the frequency rate of each characteristic response of every polar phase are correlated with the particular collective modes.