Polarized UV spectroscopy of conjugated liquid crystals

Abstract

Polarized absorption spectra of 13 nematic liquid crystals (LCs) with various conjugations and structures were measured in the spectral range from 185 to 400 nm. These absorption bands represent all the π→π* electronic transitions of these LCs. Resonance wavelength, absorption coefficient, and dichroic ratio of each band were characterized. The contribution of each band to LC birefringence is briefly discussed. Some structural effects on the LC absorption are illustrated. These absorption spectra will also serve as valuable data bases for further theoretical calculations on the band structure of LC molecules.