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SYSA: Symposium Tayloring Organic Interfaces: Molecular Structures and Applications
SYSA 5: Poster Session SYSA
SYSA 5.74: Poster
Dienstag, 26. Februar 2008, 14:30–20:00, Poster A
Metal-phthalocyanine sub-monolayer films on Ag(111): An x-ray standing wave study of CuPc, TiOPc and SnPc — •Ingo Kröger1, Christoph Stadler1, Florian Pollinger1, Andreas Stahl1, Felix Erfurth1, Benjamin Stadtmüller1, Christian Kumpf1, and Eberhard Umbach1,2 — 1Universität Würzburg, Experimentelle Physik II, 97074 Würzburg — 2Forschungszentrum Karlsruhe GmbH, D-76021 Karlsruhe
Metal-phthalocyanine (Me-Pc) molecules adsorbed in sub-monolayer structures on Ag(111) exhibit a very interesting ordering phenomenon due to intermolecular repulsion (see contribution of C. Kumpf et al.). Key aspects for the understanding of this observation are the local bonding mechanism and the adsorption geometry of the molecules. We investigated these aspects for the planar CuPc and the non-planar TiOPc and SnPc molecules on Ag(111) using the x-ray standing wave (XSW) technique, which is a highly accurate method for getting geometric data of molecules in the monolayer regime. It yields information about (vertical) bonding distances and the deformation of the molecule upon adsorption, and therefore allows to elucidate the bonding mechanism. We present XSW data of different (disordered, commensurate, and incommensurate) phases for each of the molecules. Beside a molecule-surface interaction via the central metal atom, the data indicates chemisorption mediated by the pi-system of the molecules which decreases with increasing coverage.