Berlin 2005 – scientific programme

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O: Oberflächenphysik

O 45: Organische Dünnschichten IV

O 45.1: Talk

Tuesday, March 8, 2005, 15:45–16:00, TU EB301

Molecular distortions and chemical bonding of a large π-conjugated molecule on a metal surface — •F. S. Tautz¹, A. Hauschild², K. Karki¹, B.C.C. Cowie³, M. Rohlfing¹, and M. Sokolowski² — ¹International University Bremen, School of Engineering and Science, PO Box 750761, D-28725 Bremen — ²Institut für Physikalische und Theoretische Chemie, Universität Bonn, Wegelerstr. 12, D-53115 Bonn — ³European Synchrotron Radiation Facility, Bote Postale 220, 38043 Grenoble Cedex, France

We report an experimental and theoretical investigation of the chemical bonding of 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) on Ag(111). Normal incidence x-ray standing wave experiments and density functional theory reveal that PTCDA chemisorbs on Ag(111) in a non-planar, vertically distorted configuration. The carboxylic O atoms are 0.018 nm closer to the surface than the perylene core. The distortion is related to weak local bonds between carboxylic O atoms and the Ag surface which are coupled - through charge transfer into the former lowest unoccupied molecular orbital - to the primary, extended chemisorption bond via the perylene skeleton.