Hamburg 2001 – scientific programme
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SYOF: Organische Festkörper
SYOF 2: Surfaces and Interfaces
SYOF 2.2: Talk
Tuesday, March 27, 2001, 11:50–12:05, S6
The electronic properties of highly ordered organic thin films: HBC on Au(111) by UPS and STS — •Holger Proehl1, Michael Toerker1, Torsten Fritz1, Farid Sellam1, Klaus Müllen2, and Karl Leo1 — 1Institut für Angewandte Photophysik, Technische Universität Dresden, 01062 Dresden — 2MPI für Polymerforschung, Ackermannweg 10, 55128 Mainz
We have prepared highly ordered thin films of hexa-peri -hexabenzocoronene (C42H18, HBC) on crystalline surfaces by organic molecular beam epitaxy, in UHV[1]. The electronic properties of HBC thin films adsorbed on the Au(111) surface were investigated by ultraviolet photoemission spectroscopy (UPS). The highest occupied HBC-related state is found 1.3..1.4 eV below the Au Fermi edge. Work function changes indicate an interface dipole related shift of the vacuum levels of -0.8 eV at the HBC-Au interface. The next occupied states of the HBC-films are observed at a binding energy of 1.7 eV and 2.3 eV. The angular distribution of the emission from HBC-related states changes with increasing film thickness, from submonolayers to multilayers, and can be related to changes in both the film morphology and the binding-situation. A comparison with results of scanning tunneling spectroscopy (STS) measurements shows that both methods give comparable results for the electronic structure of the occupied states for multilayer coverages of HBC.
[1] T. Fritz, Molecular Architecture in Heteroepitaxially Grown Organic Thin Films, s.f.p.s. Wissenschaftlicher Fachverlag, Dresden 1999