SURFACE ORDERING NEAR THE SMECTIC-A-SMECTIC-C TRANSITION IN THIN, FREESTANDING, LIQUID-CRYSTAL FILMS

Optical reflectivity measurements have been conducted near the smectic -A-smectic-C phase transition in free-standing films with thickness be tween two and eleven molecular layers. The temperature dependence of t he reflectivity in thin film differs significantly from that in hick f ilms. The optical thickness per layer increases in films with two to f ive layers as a result of cooling, in contrast with thick films, The a verage layer spacing was found to decrease with decreasing him thickne ss. (C) 1997 American Institute of Physics.