Berlin 2008 – scientific programme
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O: Fachverband Oberflächenphysik
O 8: Metal Substrates: Adsorption of Organic/Bio Molecules I
O 8.1: Talk
Monday, February 25, 2008, 12:00–12:15, MA 041
Surface stress and its consequences: In-situ study of PTCDA induced faceting of vicinal Ag(111) — •Florian Pollinger1, Pavo Vrdoljak1, Zhen Tian2, Dirk Sander2, Stefan Schmitt1, Christian Kumpf1, Achim Schöll1, Jürgen Kirschner2, and Eberhard Umbach1,3 — 1Universität Würzburg, Experimentelle Physik II, 97074 Würzburg — 2Max-Planck-Institut für Mikrostrukturphysik, 06120 Halle — 3Forschungszentrum Karlsruhe, 76021 Karlsruhe
Adsorption of organic molecules on vicinal metal surfaces is known to promote faceting and self-organized ordering on mesoscopic scales. The adsorption of PTCDA on vicinal Ag(111) surfaces leads to grating-like structures after annealing [1]. The system PTCDA/Ag(10 8 7) was investigated using two complementary techniques: An optical cantilever bending technique sensitive to changes in surface stress and spot-profile analysis low energy electron diffraction (SPA-LEED) to monitor the development of the interface structure during faceting. The data was compared to the related, non-faceting system PTCDA on Ag(111). Overall, we find a surface stress change of 0.7 N/m due to the PTCDA-induced faceting, whereas the adsorption of PTCDA without faceting induces a change of 0.4 N/m. Moreover, the data allows an explicit and unambiguous correlation of the surface stress change to the structural and morphological evolution of the interface during the adsorption of the PTCDA adlayer. In conclusion, the results provide experimental evidence for significant surface stress induced by an organic adsorbate and for its importance for faceting and long-range ordering at metal-organic interfaces. [1] X. Ma et al., APL 84, 4038 (2004)