STUDY ON MOLECULAR DIMERIZATION INDUCING THE ANTIFERROELECTRIC LIQUID-CRYSTALLINE PHASE BY MEASURING THE SMECTIC LAYER THICKNESS IN VARIOUS COMPOUNDS

We have closely measured the layer thicknesses of three different series of liquid crystals by X-ray diffraction. The layer thickness in the three series of compounds was found to be correlated with the degree of stabilizing ability for the antiferroelectric structure, though the molecular structures are almost the same. The compounds with the antiferroelectric SmC(A)* phase were of somewhat lesser layer thickness than that which the stable SmC* phase would be expected to have. This fact supports a previously proposed idea that the molecular dimerization in adjacent layers is important as the origin for the appearance of the SmC(A)* phase.