FREESTANDING FILMS ABOVE THE BULK SMECTIC-NEMATIC-ISOTROPIC TRANSITIONS

Optical reflectivity of free-standing films in the temperature interva l of the smectic phases and above the bulk smectic-nematic transition temperature has been studied. Melting phenomena have been found to be dependent on the film thickness. For thick films, nematic-like droplet s and an unstable state over the entire film have been observed above the bulk smectic-nematic transition temperature. These droplets and th e unstable state of the film look like the ''quasi-smectic'' phase pre dicted by Mirantsev [Phys. Lett. A 205 (1995) 412].