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O: Fachverband Oberflächenphysik

O 16: Organic, Polymeric, and Biomolecular Films I

O 16.7: Talk

Monday, March 26, 2007, 15:45–16:00, H42

A structural and electronic phase transition at a metal-organic interface: The role of intermolecular interactions — •S. Soubatch¹, L. Kilian², A. Hauschild³, R. Temirov¹, A. Schöll², A. Bendounan², F. Reinert², F. S. Tautz¹, M. Sokolowski³, and E. Umbach² — ¹International University Bremen (Jacobs University Bremen as of spring 2007), Bremen, Germany — ²Universität Würzburg, Würzburg, Germany — ³Universität Bonn, Bonn, Germany

For the organic semiconductor 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) adsorbed on the Ag(111) surface, it is found experimentally that molecules in the diluted and disordered phase, prepared at low temperatures, and the ordered commensurate monolayer phase are in significantly different adsorption states. This is deduced from comparison of their structural organization (LEED and STM), vertical bonding distances and intermolecular distortions (NIXSW), and the electronic properties (STS and UPS). The experimental data prove that the observed difference in properties of these two states is primarily caused by strong intermolecular interactions.