The Orientation Overgrowth of Metal-phthalocyanines on the Surface of Single Crystals. I. Vacuum-condensed Films on Muscovite

Abstract

Abstract When substrate muscovite is preliminarily heated at 300°C for one hour and then kept at 150°C to 200°C during deposition in vacuo, Cu-phthalocyanine films condensed on it show parallel b-axis orientations, including single- and triple-directional orientations. The b-axis of the crystal runs parallel to the substrate face. On the other hand, when the substrate is preliminarily heated at 400°C and then kept at 150°C, films vacuum-condensed on it occur in a standing b-axis orientation. The high-resolution electron-diffraction pattern of the film reveals that the a-, b- and c-axes of the crystal are inclined to the normal of the substrate face at angles of about 75°, 32° and 118° respectively. An electron micrograph of the film shows that as discrete crystals grow they orient themselves in either of two different directions. The crystal which assumes the standing b-axis orientation has its (31\bar3) plane almost parallel to the substrate face. Pt-phthalocyanine film also assumes the standing b-axis orientation, in which the a-, b- and c-axes of the crystal are inclined to the normal of the substrate face at angles of about 74°, 35° and 120° respectively. It turns out that the molecular plane comes in contact with the muscovite surface in the case of the standing b-axis orientation. A plausible explanation of the origin of these orientations is presented in terms of the dehyroxylation of the surface mica layer caused by the thermal treatment.