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O: Fachverband Oberflächenphysik

O 56: Metal substrates: Adsorption of organic / bio molecules VI

O 56.6: Vortrag

Mittwoch, 24. März 2010, 16:15–16:30, H36

Structure and energetics of azobenzene on Ag(111) — •Giuseppe Mercurio^1,2, Erik McNellis³, Isabel Martin⁴, Sebastian Hagen⁴, Felix Leyssner⁴, Sergey Soubatch^1,2, Jörg Meyer³, Martin Wolf^3,4, Petra Tegeder⁴, Frank Stefan Tautz^1,2, and Karsten Reuter³ — ¹Institut für Bio- und Nanosysteme 3, Forschungszentrum Jülich, 52425 Jülich, Germany — ²JARA-Fundamentals of Future Information Technology — ³Fritz-Haber-Institut der Max-Planck-Gesellschaft, 14195 Berlin, Germany — ⁴Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany

Normal Incidence X-ray Standing Wave (NIXSW) and Temperature Programmed Desorption experiments have been performed in order to determine the adsorption geometry of azobenzene on Ag(111), i.e. to define the following key parameters: vertical adsorption height of N=N bridge, tilt angle of the phenyl rings, and adsorption energy. Experimental results suggest nearly planar adsorption geometry of the azobenzene molecule, with the nitrogen atoms at a height of 3.07 Å. Adsorption energy was found to be 1.08 eV. The determined geometry is in good agreement with the theoretically predicted values (2.98 Å and 3°) obtained by DFT with semi-empirical dispersion corrections, validating therefore this calculation method. Discrepancy between experimental and theoretical adsorption energy was attributed to electronic screening of dispersive interactions at the metallic surface.