Comparison of the Fluorescence Characteristics of Dye Molecules in Liquid Crystal and Conventional Solvents

We investigated the fluorescence characteristics of hemicyanine dye molecules in conventional solvents and in the isotropic phase of liquid-crystal 4-pentyl-4'-cyanobiphenyl. Fluorescence decay lifetime of hemicyanine in liquid crystal decreased monotonically as the temperature was increased. As compared to glycerol, the fluorescence decay lifetime of hemicyanine in the isotropic phase of liquid crystal was appreciably longer. This longer decay lifetime of hemicyanine in liquid crystal can be explained by a restricted internal rotational motion of the hemicyanine molecule due to strong interaction between the dye molecule and the liquid crystal molecules as compared to other solvents. KCI Citation Count: 1