1. Physical Chemistry I, Ruhr-Universität Bochum, D-44780 Bochum, Germany
2. Faculty of Physics, University of Duisburg-Essen, Lotharstr. 1, D-47048 Duisburg, Germany
3. Solid State Theory, Friedrich-Alexander University Erlangen-Nürnberg, Staudtstr. 7B2, D-91058 Erlangen, Germany
4. Chemistry and Physics of Materials, University of Salzburg, Jakob-Haringer-Str. 2a, A-5020 Salzburg, Austria
5. Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, D-14195 Berlin, Germany
6. Department of Physics, Freie Universität Berlin, Arnimallee 14, D-14195 Berlin, Germany