Heteroepitaxial copper phthalocyanine on Au(001) studied by high-resolution X-ray photoelectron spectroscopy

We report the formation of heteroepitaxial copper phthalocyanine (CuPc) thin film grown on a reconstructed Au(001) surface and the high-resolution X-ray photoelectron spectroscopy study thereof. The deposition of CuPc onto the "5 x 20" reconstructed Au(001) surface at room temperature results in a well-ordered CuPc overlayer. The angle-resolved XPS data reveal that adsorbed CuPc is molecular and stoichiometric. The low energy electron diffraction (LEED) further shows that the overlayer is incommensurate to the substrate with its square unit mesh measured approximately 12.7 Angstrom by 12.7 Angstrom along <110> and <110> of the substrate. From the combined XPS and LEED data, a model of one flat-lying CuPc molecule per unit cell, which is different from the structures of the well-known alpha- and beta-polymorphs, is proposed. (C) 2003 Elsevier Science B.V. All rights reserved.