1. Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum, 44780 Bochum, Germany
2. Department of Physics, Technische Universität Dortmund, 44227 Dortmund, Germany
3. Department of Chemical Engineering, University of California, Santa Barbara, California 93106-5080, USA
4. Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106-9510, USA