Berlin 2012 – scientific programme
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O: Fachverband Oberflächenphysik
O 87: Surface chemical reactions
O 87.4: Talk
Friday, March 30, 2012, 11:15–11:30, MA 042
Reaction of Monolayer and Multilayer 2H-Phthalocyanine with a Cu(111) Surface — •Min Chen1, Jie Xiao1, Hans-Peter Steinrück1, and J. Michael Gottfried2 — 1Friedrich-Alexander-Universität Erlangen-Nürnberg — 2Philipps-Universität Marburg
The in-situ metalation of adsorbed tetrapyrrole molecules (e.g., porphyrins and phthalocyanines) continues to be a subject of interest. To clarify the mechanism of the initial interaction and subsequent reaction of 2H-phthalocyanine (2HPc) with a Cu(111) surface, various coverages of 2HPc vapor-deposited onto Cu(111) were studied by X-ray photoelectron spectroscopy (XPS) and temperature programmed desorption (TPD). It was found that adsorbed 2HPc is partially or completely metalated by reaction with Cu atoms from the substrate at 300 K, while for other tetrapyrroles such as 2H-tetraphenylporphyrin and 2H-tetrakis(3,5-di-tert-butylphenyl)porphyrin no metalation was observed under these conditions. The differences in reactivity may be related to the specific molecular geometries, which lead to the different distances between the reactive molecular center and the substrate. Furthermore, the metalation mechanism of 2HPc multilayers on Cu(111) will be discussed; in particular the question whether Cu atoms detach from the substrate and diffuse into the 2HPc multilayer or whether the 2HPc molecules in the multilayer migrate to the Cu/organic interface. Our XPS and TPD results suggest that the surface-confined metalation reactions depend critically on the molecular geometry.