Polarized Fluorescence Studies of Orientational Order in Some Nematic Liquid Crystals Doped with Stilbene Dye

Abstract

The measurements of the polarized fluorescence intensity for a stilbene guest molecule dissolved in nematic liquid crystals (5CB, 7CB and PCH7) have been used to study the molecular orientational order in thin aligned samples. The temperature dependence of the order parameters ⟨P₂⟩ and ⟨P₄⟩ have been investigated. The attempt for the explanation of the different behaviour of ⟨P₄⟩ parameter in the various liquid crystals has been undertaken. On the basis of the experimental ⟨P₂⟩ and ⟨P₄⟩ values some information about the orientational distribution of molecules in guest-host mixture have been obtained.