Critical adsorption at the free surface of a smectic liquid crystal possessing a second-order phase transition

The surface-induced molecular tilt near the second-order smectic-A (untilted)-smectic-C (tilted) transition is studied in freely suspended films consisting of hundreds of molecular layers. As the bulk transition temperature T-c is approached from above, the overall amount of the surface-induced tilt, which is far above T-c restricted to a few molecular layers near the surface, grows in a divergencelike behavior. The experimental results are compared with the Fisher-de Gennes model of critical adsorption.