The Orientation Overgrowth of Metal-phthalocyanines on the Surface of Single Crystals. II. Vacuum-condensed Films of Copper-phthalocyanine on Alkali Halides

Abstract

Cleaved faces of KCl, KBr and NaCl crystals were used as substrates. When copper-phthalocyanine is vacuum-condensed onto either KCl or KBr, the films on it take a standing b-axis orientation, which shows a C4v symmetry. The major planes of symmetry coincide with those of KCl and KBr. The crystals on KBr show an azimuthal angular shift of about +12° or –12° in respect to the major symmetry axes, [010] and [100], of the substrate crystal. When the films have the standing b-axis orientation, the planar molecule in the crystal comes into parallel contact with the cleavage face of the substrate. It may be presumed that the bridge nitrogen atoms in a phthalocyanine molecule are placed on the potassium ions in the (001) planes of KCl and KBr. The films on KCl and KBr are composed of finely-divided rectangular crystals and dendrites; the former are concentrated at steps on the cleavage face to produce a decorative pattern, while the latter appear on the smooth surface. The formation in various types of crystals are interpreted in terms of the rate of nucleation and growth. The films vacuum-condensed onto NaCl are composed of laminar crystals which have a random orientation.