Orientation of molecules in phenylene oligomer thin films : influence of the substrate temperature

Para-terphenyl, para-quaterphenyl and para-hexaphenyl thin films were obtai ned by vacuum sublimation on substrates at various temperatures (413K, 300K and 77K), Depending on the substrate temperature two types of oligomer mol ecule orientation were observed by X-ray diffraction and confirmed by spect roscopic characterizations. This two "types" of preferred orientation repre sent preferred grown crystallites; within one type obtained at "low tempera ture" the molecules are oriented parallel to the substrate, the other type is characterized by molecules approximately perpendicular to the substrate surface.