Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 7: Metal substrates: Adsorption of organic / bio molecules I

O 7.4: Vortrag

Montag, 26. März 2012, 11:15–11:30, A 053

Dissecting an organic-metal bond by molecular manipulation — •Christian Wagner, Norman Fournier, Christian Weiss, Ruslan Temirov, and F. Stefan Tautz — Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, 52425 Jülich, Germany and JARA-Fundamentals of Future Information Technology

Scanning probe microscopy with a dynamic AFM has been able to answer some fundamental questions of surface science, like the force necessary to move an atom[1]. Recently, we demonstrated the gradual removal of a single 3,4,9,10-perylenetetracarboxylic-dianhydride (PTCDA) molecule from Ag(111) using a dynamic AFM [2]. The continuous force gradient measurement allowed the structural control over the junction. Here, we show how to extract details of the molecule-surface bonding (physisorption, chemisorption, bonding via functional groups) from such an experiment. The importance of a full-fledged simulation of the lifting -including tip oscillation- is emphasized. We point out the necessity of, and fundamental problems related to, a curved tip trajectory. We study PTCDA on Au(111) and Ag(111) and find qualitatively and quantitatively different binding potentials and adsorption energies. The data represents a good benchmark for existing and future ab-initio calculations on these systems. Our method should be applicable to various substrate-adsorbate systems and hence has the potential to answer many open questions in the field.
[1] M. Ternes et al., Science 319, 1066 (2008)
[2] N. Fournier et al., Phys. Rev. B 84, 035435 (2011)