Dresden 2006 – wissenschaftliches Programm

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O: Oberflächenphysik

O 47: Organic films IV

O 47.1: Vortrag

Freitag, 31. März 2006, 11:15–11:30, PHY C213

Comparison of the vertical bonding distances of PTCDA on Ag(111) and Au(111) — •S. K. M. Jönsson¹, O. Bauer¹, A. Hauschild², T.-L. Lee³, M. Sokolowski², and F. S. Tautz¹ — ¹School of Engineering and Science, International University Bremen, P.O. Box 750561, 28725 Bremen, Germany — ²Institut für Physikalische und Theoretische Chemie, University of Bonn, 53115 Bonn, Germany — ³European Synchrotron Radiation Facility, Bote Postale 220, 38043 Grenoble Cedex, France

The model molecule PTCDA adsorbs on the Au(111) and Ag(111) surfaces in a planar configuration forming long range ordered superstructures. However, from different electron spectroscopies, STM and LEED data there is evidence that the bonding strength of PTCDA on Ag(111) is stronger than on Au(111). Hence the question arises, whether this also leads to a change of the vertical bonding distance of PTCDA with respect to the underlying surface. For this purpose we have measured the vertical distance of the carbon skeleton of PTCDA with respect to both surfaces using the normal incidence standing wave technique (NIXSW). Interestingly, we find that the bonding distance on Au(111) is by 0.4 Å(or 15 %) larger than on Ag(111), in agreement with the expectation on the basis of a weaker bonding. This work was supported by the DFG and the ESRF.