Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 7: Metal substrates: Adsorption of organic / bio molecules I
O 7.7: Vortrag
Montag, 26. März 2012, 12:00–12:15, A 053
Modification of the PTCDA/Ag(111) interaction by the formation of a hetero-organic interface with CuPc — •Benjamin Stadtmüller1,2, Tomoki Sueyoshi1,2, Serguei Soubatch1,2, F. Stefan Tautz1,2, and Christian Kumpf1,2 — 1Peter Grünberg Insitut (PGI-3), Forschungszentrum Jülich, Germany — 2Jülich-Aachen Research Alliance - Fundamentals of Future Information Technology
In recent years the adsorption of large organic molecules on noble metal surfaces has been studied in great detail. One key aspect in these studies was the characterization of the interaction between the organic adsorbates and the metal substrate. Based on these studies we have now started to investigate hetero-organic systems consisting of more than one molecular species. Here we present a X-Ray Standing Waves (XSW) and photoelectron spectroscopy (UPS) study of the adsorption behavior of CuPc on one closed layer of PTCDA on Ag(111). The CuPc molecules adsorb on top of the closed PTCDA layer and form a disordered CuPc layer at submonolayer coverages and room temperature, which condenses into the commensurate 'stacked bilayer'-structure upon cooling below 160K. XSW reveals an adsorption height of CuPc on PTCDA which is significantly smaller than the sum of the van der Waals radii of the atomic species. Even more interestingly, for this system the vertical adsorption geometry of the underlying PTCDA molecule changes: The molecular backbone is pushed towards the silver surface. Furthermore, UPS experiments reveal a shift of the PTCDA F-LUMO. These results clearly indicate a modified interaction between PTCDA and the silver surface by the adsorption of CuPc.