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O: Oberflächenphysik

O 38: Adsorption an Oberflächen III

O 38.7: Talk

Thursday, March 11, 2004, 17:15–17:30, H38

Adsorption geometry of Palladium Phthalocyanine (PdPc) on Graphite: STM and LEED investigations — •T. G. Gopakumar, M. Lackinger, F. Müller, and M. Hietschold — Chemnitz University of Technology, Institute of Physics, Solid Surfaces Analysis Group, D-09107, Chemnitz, Germany

Adsorption geometry of planar Palladium Phthalocyanine (PdPc) molecules on natural graphite was studied using a variable temperature STM and LEED. PdPc films were prepared on a freshly cleaved natural graphite (0001) surface using Organic Molecular Beam Epitaxy (OMBE) under UHV conditions at room temperature. It was observed that PdPc molecules were adsorbed with their molecular planes parallel to the substrate and forming highly ordered phases with quadratic lattices. Further analysis to find the orientation of molecular super-lattice with respect to the graphite lattice vectors shows a rotation of 10 degree. For a better understanding of the submolecular contrast, the software package Gaussian 98 was used to calculate the electronic structure of isolated PdPc molecules. The different STM contrast could be explained and electronic analogies were found.