Visco-Elastic Properties of Some Nematic Liquid Crystals

Abstract
We report on some temperature dependent visco-elastic properties of di-butyl-azoxy-benzene (Dibab) and 4 methoxy-4′-azoxy-benzene (N4) which have their nematic temperature range from 19.5 to 31.5[ddot]C and 16 to 76[ddot]C respectively. The results are obtained by studying the noise intensity spectrum of Rayleigh scattered laser light. Experiments are done using both homodyne and heterodyne techniques. From the configuration where the director is perpendicular to the plane of observation we obtained both the splay-bend and the twist-bend slow mode.