EVALUATION OF TILT ANGLES OF NEMATIC LIQUID-CRYSTAL MOLECULES ON POLYIMIDE LANGMUIR-BLODGETT-FILMS USING THE ATTENUATED TOTAL-REFLECTION MEASUREMENT METHOD

The tilt angles of liquid crystal molecules, 5CB, have been investigat ed in liquid crystal cells with rubbing-free aligning layers of polyim ide (PI) Langmuir-Blodgett (LB) films on aluminum electrodes using the attenuated total reflection (ATR) measurement method. The surface pla smon polariton (SPP) and/or the guided wave excitation modes (GWEM) we re observed in the ATR curves of the liquid crystal cells when various DC voltages were applied to the cell. The ATR properties were evaluat ed from the SPP and the GWEM. The tilt angles of the liquid crystal mo lecules were calculated by fitting the theoretical ATR curves to the e xperimental ones using various models of the liquid crystal layer stru cture. Furthermore, the electric field intensities in the cell were ca lculated at several incident angles in the ATR curves. The ATR measure ment is very useful for evaluating the alignment properties of liquid crystal molecules in liquid crystal cells.