Low-temperature structural study of smectic C$_A$* glass by X-ray diffraction

Abstract: The liquid crystalline compound, forming the glass of the smectic C$_A$* phase, is investigated by the X-ray diffraction in the 18-298 K range. The characteristic distances within the smectic C$_A$* phase are determined. The electron density profile along the smectic layer normal is inferred and compared with the results of the density functional theory calculations. Observations of the selective reflection of the visible light investigate the helical ordering within the smectic C$_A$* glass. The results indicate slow evolution of the smectic layer spacing, intermolecular distances, and electron density distribution below the glass transition temperature. Meanwhile, the relative range of the short-range order within the smectic layers and the helix pitch are relatively constant in the glassy state.