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O: Fachverband Oberflächenphysik

O 18: Organic/bio Molecules on Metal Surfaces II

O 18.9: Vortrag

Montag, 11. März 2013, 18:00–18:15, H38

Adsorption and thermal polymerization of pentacene on Ir(100) — •Pascal Ferstl, Lisa Lautner, Lutz Hammer, and M. Alexander Schneider — LS f. Festkörperphysik, FAU Erlangen-Nürnberg, Germany

Pentacene molecules were deposited at various temperatures on both the unreconstructed and the quasi-hexagonally reconstructed surface phases of Ir(100) and subsequently thermally processed. On both surfaces the molecules adsorb flat lying, they are immobile at room temperature, but apparently intact. On the fourfold symmetric 1x1 phase there is basically only one particular binding configuration for the molecules, which is either along the [011] or the [011] direction and they randomly assume one of these two (symmetry-equivalent) orientations without any tendency to form ordered domains.

On the one-dimensionally corrugated (5x1) phase the pentacene species deposited at room temperature show three different binding configurations: along the rows of the reconstruction, or inclined by 30^∘ or 90^∘. Increasing the deposition temperature to above 100^∘C the adsorption site within the troughs of the reconstruction becomes more and more dominant. For deposition (or annealing) temperatures above 360^∘C the molecules successively decompose towards a surface carbide. At intermediate temperatures, however, one-dimensional head-to-tail polymerization is found leading to molecular chains of at least double or triple length, which are not observed on the (1x1) phase. This indicates that the substrate reconstruction acts as a template for the molecular reaction scheme at the surface.