Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 52: Metal substrates: Adsorption of organic / bio molecules VII
O 52.2: Vortrag
Donnerstag, 26. März 2009, 15:15–15:30, SCH A118
Systematic study of phthalocyanine (sub-)monolayer phases by high-resolution PES and NEXAFS — •M. Häming1, C. Scheuermann1, E. Umbach1,2, A. Schöll1, and F. Reinert1,2 — 1Universität Würzburg, Experimentelle Physik II — 2Forschungszentrum Karlsruhe, 76021 Karlsruhe
The interaction at metal-organic interfaces is crucial for electronic devices, since it influences the morphology and the electronic structure at the interface, and consequently the charge transport through metal-organic contacts. Therefore we investigate the interaction and interplay between the geometric and electronic structure at a metal-organic model interface. We study systematically various (sub-)monolayers phases of flat lying phthalocyanine on the Ag(111) surface by high-resolution photoemission spectroscopy (PES) and near edge x-ray absorption fine structure spectroscopy (NEXAFS). We observe evidence for chemisorption of the molecules in all spectra (valence band, NEXAFS and core levels). Moreover, already small differences in the adsorption geometry between the different phases change the respective spectra and the work function significantly. For example, an increase in coverage leads to a weaker interface bond. Consistent changes in the valence band and NEXAFS spectra indicate that consequently the occupation of the former molecular LUMO level, which is partly occupied due to the chemisorption, is altered. Our investigation demonstrates that the electronic structure at interfaces is very sensitive to relatively small changes in the interaction, and that high-resolution PES and NEXAFS are powerful techniques to study these correlations.