Crystalline transitions in free-standing films of 4-n-heptyloxybenzylidene-4-n-heptylaniline

Free-standing films of 4-n-heptyloxybenzylidene-4-n-heptylaniline are known to exhibit multiple smectic-l surface layers in the presence of a smectic- A interior. The phase transitions leading to the crystallization of these f ilms have been studied using electron diffraction. Our data are consistent with the scenario of the smectic-l surface layers first developing a crysta l-B outermost layer before transforming entirely into the crystal-B phase, to be followed by the freezing of the smectic-A interior. The adjacent crys tal-B and smectic-I layers show evidence of orientational epitaxy.