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O: Fachverband Oberflächenphysik

O 49: Metal substrates: Adsorption of organic / bio molecules VI

O 49.7: Vortrag

Mittwoch, 16. März 2011, 16:30–16:45, PHY C213

The adsorption geometry and bonding properties of PTCDA on Ag(110) — •Oliver Bauer¹, Giuseppe Mercurio², Sergey Subach², Benjamin Fiedler¹, Christoph H. Schmitz¹, Frank Stefan Tautz², and Moritz Sokolowski¹ — ¹Institut für Physikalische und Theoretische Chemie, Universität Bonn — ²Peter Grünberg Institut (PGI-3), Forschungszentrum Jülich, und JARA-Fundamentals of Future Information Technology

The vertical bonding distance of an adsorbate to the underlying surface can be regarded as a quantity related to the strength and the chemisorptive character of the bond. The Normal-Incidence X-ray Standing Wave (NIXSW) technique has recently been used to determine the bonding distance of perylene-3,4,9,10-tetracarboxylic acid dianhydride (PTCDA) on (111) coinage metal surfaces [1]. In addition, we have investigated the adsorption geometry of PTCDA in the monolayer regime on the more open Ag(110) surface: We find a bonding distance of the perylene core to the substrate which is significantly smaller than the sum of the vdW radii of both Ag and C, indicating a strong chemical interaction. Furthermore, the PTCDA molecule adsorbs in an arc-like geometry with the O atoms being even closer to the surface than the perylene core. This hints at strong local, covalent Ag-O intercations. The experimental results are discussed in the framework of the Newns-Anderson model and the recent finding, that for coinage metal (111) surfaces the adsorption height of PTCDA correlates with the work function of the bare substrate [1]. Supported by the DFG and the ESRF. [1] a.o. A. Hauschild et al., PRB 81 (2010) 125432.