Evidence for the presence of a twist-grain-boundary structure in confined hybrid non-chiral smectic liquid crystal films

We have used Grazing Incidence X-ray Scattering to study the depth dependence of the interfacial structure of smectic liquid crystal (8CB) hybrid films. These films are bounded by a grated glass substrate and air, and have been studied as a function of both temperature and thickness. Our measurements indicate the presence of both a chevron structure and a structure similar to the helical twist-grain-boundary (TGB) phase. Our measurements constitute the first to show that this structure can also be observed in hybrid smectic liquid crystal films. The twisted structure is the result of anchoring at two dissimilar competing confining surfaces.