Berlin 2008 – wissenschaftliches Programm
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SYSA: Symposium Tayloring Organic Interfaces: Molecular Structures and Applications
SYSA 5: Poster Session SYSA
SYSA 5.69: Poster
Dienstag, 26. Februar 2008, 14:30–20:00, Poster A
Monolayer to multilayer transition of hexa-peri-hexabenzocoronene on Ag(111) — •Hendrik Glowatzki1, Gianina N. Gavrila2, Stefan Seifert2, Robert L. Johnson3, Hans Joachim Räder4, Klaus Müllen4, Dietrich R.T. Zahn2, Jürgen P. Rabe1, and Norbert Koch1 — 1Humboldt-Universität zu Berlin, Institut f. Physik, Newtonstr. 15, D-12489 Berlin — 2Technische Universität Chemnitz, Institut f. Physik, Reichenhainer Str. 70, D-09126 Chemnitz — 3Universität Hamburg, Institut f. Experimentalphysik, D-22761 Hamburg — 4Max Planck Institut für Polymerforschung, D-55021 Mainz
The properties of hexa-peri-hexabenzocoronene (HBC) deposited on Ag(111) in the mono- and multilayer regimes were investigated by several complementary techniques. The molecular orientation was determined by near-edge x-ray absorption fine structure spectroscopy (NEXAFS), scanning tunneling and scanning force microscopy (STM, SFM), and the electronic structure by ultraviolet photoelectron spectroscopy (UPS). We found that the molecular orientation changed as a function of coverage; at monolayer coverage the HBC molecules were aligned parallel to the substrate whereas in the multilayer the molecules were tilted by 43°. This structural transition was accompanied by a rigid shift of the molecular energy levels by 0.3 eV towards higher binding energy between mono- and multilayer coverage. In addition, the highest molecular levels in the multilayer were broadened by 0.35 eV, suggesting the formation of extended intermolecular energy bands.