Nature of the layer-by-layer transition associated with the smectic-A-crystal-B transition in free-standing liquid-crystal films.

Abstract

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=${\mathit{L}}_{0}$\ensuremath{\Vert}t${\mathrm{\ensuremath{\Vert}}}^{\mathrm{\ensuremath{-}}\ensuremath{\nu}}$ with \ensuremath{\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.