Regensburg 2007 – scientific programme
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O: Fachverband Oberflächenphysik
O 58: Metal Substrates: Adsorption IV
O 58.6: Talk
Thursday, March 29, 2007, 17:00–17:15, H39
Copper-Phthalocyanine on Ag(111) - A SPA-LEED study — •Ingo Kröger, Christoph Stadler, Christian Kumpf, and Eberhard Umbach — Universität Würzburg, Experimentelle Physik II, Am Hubland, 97074 Würzburg
The adsorption of Copper-Phthalocyanine (CuPc) on Ag(111) has been studied by Spot Profile Analysis Low Energy Electron Diffraction (SPA-LEED). Three different phases were found in the submonolayer regime, differing in coverage and temperature.
At coverages below 0.8 layers and at room temperature no long-range order was observed. However, from diffuse rings in LEED we could still determine an average distance between the molecules which decreases continuously with increasing coverage.
Between 0.8 and 1.0 layers CuPc forms incommensurate superstructures. The unit cell size shrinks continuously from 216Å2 (0.8 ML) to 196Å2 (1.0ML). These measurements show that the molecules (at RT) always occupy the maximum surface area, a behaviour which is only compatible with a repulsive intermolecular interaction and a relatively small influence of the substrate.
Furthermore, at coverages between 0.7 -0.8 layers a low temperature phase was found, which is commensurate with the substrate. Very recently the same behaviour was found for SnPc on Ag(111).