Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 7: Metal substrates: Adsorption of organic / bio molecules I
O 7.6: Vortrag
Montag, 26. März 2012, 11:45–12:00, A 053
Importance of electron correlations for π-conjugated organic molecules on metal substrates — •Christoph Sauer1,2, Florian Bruckner1,2, Holger Wetzstein1,2, Sina Gusenleitner1,2, Achim Schöll1,2, and Friedrich Reinert1,2 — 1Physikalisches Institut, Experimentelle Physik VII und Wilhelm Conrad Röntgen Research Center for Complex Material Systems (RCCM), Universität Würzburg, D-97074 Würzburg — 2Gemeinschaftslabor für Nanoanalytik, Karlsruher Institut für Technologie KIT, D-76021 Karlsruhe
We demonstrate that electron correlations play an important role for the energy balance when the adsorption of π-conjugated molecules on metal substrates leads to charge transfer into the former lowest unoccupied molecular orbital (LUMO). By annealing an organic heterostructure of tin-phthalocyanine (SnPc) on top of a Ag(111) surface precovered with one monolayer (ML) of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) we produce a pure ML of SnPc on Ag(111). Therefore our high resolution photoemission spectroscopy (PES) analysis proves that the adsorption of SnPc is energetically favoured over PTCDA on Ag(111). We identify that this behavior is a consequence of a smaller Coulomb repulsion (UC) between the electron in the former LUMO and the electrons in the other molecular orbitals for SnPc. The difference in UC for SnPc and PTCDA is demonstraded by a comparison of PES and inverse PES data from multilayer and ML samples and values in the order of 1 eV are found. Hence UC is not negligible for the adsorption energy balance.