Thickness Dependence of the Glass-Liquid Crystal Buried Interface Structure

Abstract

We have used Grazing Incidence X-ray Diffraction (GIXS) to study the structure of a smectic A liquid crystal (LC) at the buried LC-glass interface in liquid crystal films. This measurement is done in reflection mode through the glass substrate, which consists of a grating photolithographed onto a 0.2 mm thick slide. The observed in-plane alignment indicates the presence of tilted layers within 50Å of the glass interface, inside the grooves. These layers correspond to the tilted region observed previously in samples confined within the grating grooves. The tilted layer region is suppressed by the grating induced homogeneously aligned LC layers, which act as a new confining boundary that modifies the LC structure within the grooves. The interaction between the two observed in-plane regions depends on the thickness of the LC films as well as the depth of the gratingś grooves.