Rotatory Dispersion of Cholesteric Liquid Crystals

Abstract

Measurements of rotatory dispersion and circular dichroism of (i) a mixture of nematic p-methoxybenzylidene-p'-butylaniline (MBBA) and spectratherm (ii) a mixture of cholesteryl benzoate and nematic p-azoxyphenetole (PAP) and (iii) cholesteryl cinnamate for different thicknesses have been made. The experimental data on cholesteryl cinnamate are in qualitative agreement with the theoretical predictions of Dreher et al., ⁽¹⁾ Chandrasekhar and Shashidhara Prasad⁽²⁾ and Aihara and Inaba.⁽³⁾ Also the results of the mixtures are in qualitative agreement with the theoretical predictions, that for thick specimens the circular dichroism plotted as a function of wavelength should exhibit a flat top maximum. An attempt has been made to fit the rotatory dispersion and circular dichroism data of cholesteryl cinnamate. It is found that the same constants can be used to explain our data as well as that due to Mathieu,⁽⁴⁾ approximately well.