Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 52: Metal substrates: Adsorption of organic / bio molecules VII
O 52.4: Vortrag
Donnerstag, 26. März 2009, 15:45–16:00, SCH A118
Adsorption energy and geometry of adsorbed organic molecules on Au(111) probed by surface-state photoemission — •Johannes Ziroff1, Frank Forster1, and Friedrich Reinert1,2 — 1Universität Würzburg, Experimentelle Physik II , D-97074 Würzburg, Germany — 2Forschungszentrum Karlsruhe, Gemeinschaftslabor für Nanoanalytik, D-76021 Karlsruhe, Germany
The modification of the Au(111) surface states by an adsorbed monolayer of large π-conjugated molecules (PTCDA, NTCDA, CuPc) was investigated by high-resolution angle-resolved photoelectron spectroscopy. We determined binding energy, band mass, and Rashba-splitting and discuss the results in the context of rare-gas adsorption on noble metals. This comparison allows the determination of the bonding strength of the adsorbates, found to be physisorptive with derived binding energies per molecule of 2.0 eV for PTCDA and 1.5 eV for NTCDA. We will also present a superstructure model for the NTCDA/Au(111) system, deduced from low energy electron diffraction images in combination with band-backfolding of the Tamm and Shockley states. The coverage dependent evolution of the surface states was also investigated for the three molecules, giving evidence for a dilute-phase growth of the CuPc molecule on the Au(111) surface.