Characterization of a new helical smectic liquid crystal

Abstract

The discovery of the first liquid-crystalline material in 18881,2 also heralded an age of fascination with chirality and optical activity in ordered fluids. The cholesteric mesophase, which was the first liquid crystal to be found, exhibits form optical activity by virtue of a helical arrangement of its constituent molecules. One hundred years after the discovery of this first liquid crystal, we report the discovery of a new helical smectic liquid crystal, the smectic-A* phase. In this phase the lath-like molecules are arranged in layers with their long axes on average normal to the layer planes. Parallel to the layers there is a helical ordering of the molecules (Fig. 1). We suggest that this phase may be described by a model in which grain boundaries of screw dislocations rotate blocks of layers with respect to each other.