APPLICATION OF INFRARED ATR SPECTROSCOPY TO LIQUID CRYSTALS - 3.

Infrared absorption measurements of nematic N-(p-ethoxybenzylidene)-p prime -cyanoaniline (EBCA) under a DC electric field were performed by means of ATR method. DC voltages up to 15 V were applied to the nematic liquid crystal 15 mu m thick between a silicon ATR prism (probing electrode) and an In//2O//3-coated glass electrode (opposite electrode). By using this method the orientational behavior of molecules in boundary layers about 1 mu m thick at the Si electrode was investigated. The threshold voltage for the dielectric orientation varied from 2 to 6 V depending upon the boundary conditions at the opposite electrode, and the maximum degree of order of homeotropic orientation was found to be 0. 6-0. 7. A storage effect, in which a homeotropic texture induced by the electric field remains unaltered even if the field is removed or reversed, was observed.