Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 35: Poster Session I (Metal, semiconductor and oxide substrates: structure and adsorbates; Graphene)

O 35.13: Poster

Dienstag, 12. März 2013, 18:15–21:45, Poster B1

PTCDA on Cu(100) re-investigated by STM — •Stefan Gärtner, Benjamin Fiedler, Oliver Bauer, and Moritz Sokolowski — Institut für Physikalische und Theoretische Chemie der Universität Bonn, Germany

Whether the adsorption of an organic adsorbate on a metal surface leads to ordered or disordered structures, possibly including molecular dissociation, depends on the interfacial chemistry. While PTCDA forms long-range ordered structures on all Au and Ag surfaces, different structure models [1,2] and even a molecular dissociation were discussed for PTCDA on Cu(100) on the basis of XPS data [1]. To clarify this we have performed so far missing STM investigations. Indeed, for Cu(100), we find that the preparation of long-range ordered structures requires elevated sample temperatures (400 K), pointing to a considerable corrugation of the surface bonding potential. However, from the STM images, we obtain no indications for dissociation. We put forward a structure model with an L-type arrangement of the molecules in the monolayer and the second layer in agreement with the proposed (5√2 × 4√2)R45^∘ structure of ref. [1]. The lattice parameters of this model are in full agreement with our LEED results on this system. Supported by SFB 624.

[1] T. J. Schuerlein et al., JVSTA 12 (1994) 1992. [2] M. Andreasson et al. Synth. Met. 158 (2008) 45