# Low-Temperature Structural Study of Smectic CA* Glass by X‑ray Diffraction

## TL;DR

This paper studies the structural properties of a smectic CA* glass using X-ray diffraction at low temperatures.

## Contribution

The study provides new insights into the temperature-dependent structural behavior of smectic CA* glass below the glass transition.

## Key findings

- The smectic layer spacing and electron density distribution change slowly with temperature below the glass transition.
- The specific volume's temperature dependence shifts well below the glass transition temperature.
- Short-range order and helix pitch remain constant in the glassy state.

## Abstract

The liquid crystalline compound, forming the glass of
the smectic
CA* phase, is investigated by X-ray diffraction in the
18–298 K range. The characteristic distances within the smectic
CA* phase are determined, and the specific volume is estimated.
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 CA* glass. The
results indicate slow change with temperature of the smectic layer
spacing, intermolecular distances, and electron density distribution
below the glass transition temperature. The change in the temperature
dependence of the specific volume is well below the glass transition
temperature. Meanwhile, the relative range of the short-range order
within the smectic layers and the helix pitch are rather constant
in the glassy state.