Electron diffraction in free-standing films of 4-n-heptyloxybenzylidene-4-n-heptylaniline of up to 25 molecular layers has revealed the coexistence, as a function of distance from the surface, of three distinct phases: an outermost smectic-l layer, several layers of a middle phase, and a smectic-A interior. The middle phase is an unusual highly-correlated tilted liquid, with hexatic like positional correlations but no long-range bond-orientational order, which transforms to the smectic-l at a lower temperature. The discovery of this unusual middle phase also represents the possibility of a novel layer-dependent two-stage tilt-induced surface-freezing transition.
關聯:
MOLECULAR CRYSTALS AND LIQUID CRYSTALS SCIENCE AND TECHNOLOGY SECTION A-MOLECULAR CRYSTALS AND LIQUID CRYSTALS
