Thin molecular films of neutral tetrathiafulvalene-derivatives

Thin films (thickness approximately 1□m) of the neutral □-donor molecules tetrathiafulvalene (TTF) derivatives tetramethyl-tetrathiafulvalene (TMTTF), ethylenedithio-tetrathiafulvalene (EDT-TTF) and bis(ethylenedithio)-tetrathiafulvalene (BEDT-TTF) as well as of tetramethyl-tetraselenafulvalene (TMTSF) have been obtained by sublimation in high vacuum (approximately 10-6 mbar) on alkali halide substrates. The films grow by the well-known Volmer-Weber mechanism and are polycrystalline. The microcrystals are highly oriented with their most densely packed molecular planes parallel to the substrate surface in order to minimize the surface (interface) energy. Incommensurate in-plane texture is found for particular molecule-substrate systems.