Orientational Behaviour of some Novel Fluoro-Substituted Liquid Crystals as Studied by Optical Spectroscopy Methods

Abstract

The long-range orientational order of eight newly synthesized fluoro-substituted liquid crystals, two with a positive dielectric anisotropy and six with a negative dielectric anisotropy, was studied by means of the optical spectroscopy methods: electronic absorption and fluorescence. The liquid crystals were doped with small amount of the fluorescent dichroic dye. The absorption and emission spectra of linearly polarized light were recorded as a function of temperature in the whole range of the mesophase. The results obtained allow to determine the order parameters〈P2 and〈P4〉as well as the orientational distribution function. An importance of the molecular structure of the liquid crystal on the orientational order was ascertained and discussed.