Dresden 2011 – scientific programme

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O: Fachverband Oberflächenphysik

O 36: Poster Session II (Metals; Nanostructures at surfaces; Surface or interface magnetism; Spin-Orbit Interaction at Surfaces; Electron and spin dynamics; Surface dynamics; Methods; Theory and computation of electronic structure)

O 36.16: Poster

Tuesday, March 15, 2011, 18:30–22:00, P4

Cobalt phthalocyanine molecules adsorbed on Ag(111): Examination of interfacial interactions — •Martin Schmid, Andre Kaftan, Min Chen, Jie Xiao, Hans-Peter Steinrück, and J. Michael Gottfried — Universität Erlangen-Nürnberg, Lehrstuhl für Physikalische Chemie II

The modification of interfacial properties by adsorbates is a fundamental aspect in catalysis and molecular electronics. As a model system for metal/organic interfaces, we studied the adsorption of Co(II)-phthalocyanine (CoPc) on Ag(111). In general, metallophthalocyanines form well ordered layers on metallic substrates. To obtain a deeper insight into the CoPc/Ag interaction, we examined submonolayers, monolayers, and multilayers of CoPc with photoelectron spectroscopy (XPS/UPS) and low-energy ion scattering (LEIS). Up to one monolayer, the adsorption of CoPc induces two new electronic states in the vicinity of the Fermi edge and a negative work-function shift. XPS shows a strong modification of the Co 2p3/2 and 2p1/2 core level states due to the CoPc-Ag(111) interaction. These levels exhibit a binding energy ~2 eV lower than in molecules without a direct contact to the metal interface. This finding can be interpreted by a charge transfer from the Ag(111) substrate into the molecules. Furthermore, the binding energy differences between the 2p1/2 and 2p3/2 levels are altered by the contact to the single crystal surface. This observation suggests a change in the electronic state of the central Co ion. Support by the DFG through SFB 583 is gratefully acknowledged.