NATURE OF THE LAYER-BY-LAYER TRANSITION ASSOCIATED WITH THE SMECTIC-A CRYSTAL-B TRANSITION IN FREESTANDING LIQUID-CRYSTAL FILMS

Utilizing our ac free-standing film calorimeter, we have observed the formation of a series of crystal-B layers at the smectic-A-vapor interface near the smectic-A-crystal-B transition of 4O.8 [N-(4-n-butyloxybenzylidene)-4-n-octylaniline]. The temperature dependence of the penetration of the crystal-B order into the smectic-A substrate can be well described by a simple power law, L = L0 Absolute value of t -nu with nu = 0.37, indicating that the dominant intermolecular interaction is van der Waals like. Further analysis has demonstrated the penetration length of the surface ordering to be slightly less than one molecular length.