Regensburg 2007 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 49: Nanostructures at Surfaces V (Self Organization of Molecules)
O 49.2: Vortrag
Donnerstag, 29. März 2007, 11:30–11:45, H36
Relaxation of surface stress induced by an organic adsorbate: PTCDA on vicinal Ag(111) — •Florian Pollinger1, Pavo Vrdoljak1, Zhen Tian2, Dirk Sander2, Dominik Fertig1, Stefan Schmitt1, Christian Kumpf1, Achim Schöll1, Jürgen Kirschner2, and Eberhard Umbach1 — 1Universität Würzburg, Experimentelle Physik II, Am Hubland, 97074 Würzburg — 2Max-Planck-Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle
Self-organization of metallic surfaces on large scales can be induced by the adsorption of organic molecules and has been observed in several experiments [1]. One example is the growth of 3,4,9,10-perylene-tetracarboxylic-acid dianhydride (PTCDA) on stepped (8.5°-vicinal) Ag(111) surfaces. At elevated temperatures, the adsorbate molecules lead to a bunching of substrate steps, which agglomerate to facets of critical sizes. The facets arrange in a coverage-dependent grating-like pattern on a mesoscopic length scale. The resulting order requires a long-range interaction which is mediated by the substrate [2]. It can be explained by a change of surface stress induced by the adsorbate layer. Experimentally, such a change is directly accessible by an optical cantilever bending technique. We monitored the bending of a faceting thin Ag(10 8 7) crystal with this method in order to quantifiy the occurring relaxation of surface stress. [1] J. I. Pascual et al. J. Chem Phys. 120, 11367 (2004) [2] Q. Chen et al., Prog. Surf. Sci. 73, 59 (2003)