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O: Fachverband Oberflächenphysik
O 6: Organic/bio Molecules on Metal Surfaces I
O 6.7: Talk
Monday, March 11, 2013, 12:00–12:15, H38
Systematic X-ray standing wave study of pentacene and pentacenederivatives on coinage metals — •Alexander Gerlach1, Christoph Bürker1, Jens Niederhausen2, Steffen Duhm3, Takuya Hosokai1, Blanka Detlefs4, Norbert Koch2, Georg Heimel2, and Frank Schreiber1 — 1Institut für Angewandte Physik, Universität Tübingen, DE — 2Institut für Physik, Humboldt-Universität zu Berlin, DE — 3FUNSOM, Soochow University, CN — 4European Synchrotron Radiation Facility, FR
We present X-ray standing wave data for pentacene (PEN), pentacenequinone (P2O) and pentacenetetrone (P4O) on Cu(111), Ag(111), and Au(111). The bonding distances d and the distortions of the absorbed molecules measured with this technique are characteristic for the interaction mechanism with the different substrates [1,2]. Depending on the number of C=O groups attached to the molecule we find surprisingly different bonding distances and adsorption geometries on the three coinage metal surfaces. On Au(111) [Cu(111)], there is a relatively weak [strong] interaction, i.e. dC ≈3.3 Å [2.3 Å], with negligible [significant] distortion of the molecules. On Ag(111), as the intermediate case, both scenarios are observed: While for PEN and P2O we find a weak substrate interaction with dC ≈3.0 Å and 3.3 Å, P4O shows a chemisorptive bonding with dC ≈2.7 Å. Finally, we discuss consequences of the different bonding behavior with regard to the electronic structure and the enery-level alignment at the organic-metal interface. [1] N. Koch et al., J. Am. Chem. Soc. 130 (2008) 7300 [2] A. Gerlach et al., Phys. Rev. B 75 (2007) 045401