SPONTANEOUS POLARIZATION PARALLEL TO THE TILT PLANE IN THE ANTIFERROELECTRIC CHIRAL SMECTIC-C-A, PHASE OF LIQUID-CRYSTALS AS OBSERVED BY POLARIZED INFRARED-SPECTROSCOPY

We have observed the absorbance vs polarizer rotation angle for the carbonyl and phenyl ring stretching peaks in an antiferroelectric liquid crystal, 4-(1-methylheptyloxycarbonyl)phenyl 4'-octyloxybiphenyl-4-carboxylate (MHPOBC),and found that the carbonyl group near the chiral center rather lies on the tilt plane in antiferroelectric Sm-C-A* while it takes a considerably upright position in ferroelectric Sm-C*. The spontaneous polarization exists at smectic layer boundaries and its importance to stabilize Sm-C-A* has been discussed.