A Structural Study of Temperature Influence on the Effect of Grated Substrates on Smectic Liquid Crystal Films

Abstract

We present a preliminary analysis of the results of our structural measurements on the influence of temperature variation on the orientation of smectic liquid crystal films deposited on photolithographed gratings on glass gratings. These gratings have periods of 10μm with depths ranging up to 2–3μm. We previously found that both silicon and glass gratings are able to align the liquid crystal along the grating direction for film thick-nesses above 15μm, in the grating period range 664nm–24μm, as determined by using both x-ray diffraction and optical microscopy. The size of the top layer and the grating period range are of the order of magnitude of the correlation length for the smectic liquid crystal film. In this study, the region just above the critical thickness in smA droplets was studied as a function of temperature beyond the smA - N transition. Special attention was given to the region of thickness around 40μm, a region where the competition between the air-liquid crystal interface and the liquid crystal-substrate interface was most pronounced. We observed a persistence of molecular order and alignment in the layer along the gratings through the smA - N transition.