Dresden 2006 – scientific programme
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O: Oberflächenphysik
O 25: Organic films II
O 25.9: Talk
Tuesday, March 28, 2006, 17:45–18:00, PHY C213
A Metal Surface as a Complex Ligand: Adsorption of Co(II)-Porphyrins on Ag(111) — •T. Lukasczyk, K. Flechtner, K. Comanici, H. Marbach, F. Maier, J. M. Gottfried, and H.-P. Steinrück — Universität Erlangen-Nürnberg, Lehrstuhl für Physikalische Chemie II, Egerlandstr. 3, D-91058 Erlangen, Germany
Metalloporphyrins control the decisive steps in various natural and technological processes that often involve the reversible attachment of a molecular ligand on the central metal ion. In order to study this key step on a model compound in a solvent-free environment, we investigated ordered monolayers of Tetraphenylporphyrin-Co(II) and Tetrakis-(3,5-di-tert-butylphenyl)porphyrin-Co(II) on Ag(111). First, we focused on the interaction of the Co-dz2 orbital with the Ag surface, because the coordination of an additional ligand is most likely mediated by this orbital. We made use of the different "heights" of the molecules to vary the distance between the Co atom and the Ag substrate. The monolayers were studied with XPS, UPS, and LEED. In the Co 2p3/2 photoemission signal, a peak appears at 778.3 eV that is absent at multilayer coverages and that probably reflects the interaction of the Co ion with the Ag substrate. Complementary evidence for this interaction is provided by a new signal close to EF in the monolayer UP spectrum. The UP signal position varies with the Co-Ag distance, as expected from MO theory. This work was supported by the DFG through SFB 583.