Electronic structures of CuPc on a Ag(110) surface

Abstract

Copper phthalocyanines (CuPc) on a Ag(110) surface have been studied by ultraviolet photoemission spectroscopy (UPS). On depositing CuPc organic films, the features from the substrate 3d valence fade and four new features corresponding to the adsorbed molecules emerge at 1.68, 4.45, 6.36 and 9.20 eV below the Fermi level. These features shift in binding energy with increasing thickness of the organic films. In the case of a monolayer, angle-resolved UPS measurements suggest that the molecular plane is nearly parallel to the substrate. Further theoretical calculation indicates that the adsorption of CuPc on a hollow site is the most favourable configuration, and the separation between the adsorbate and the substrate is about 2.7 Å.