1. Department of Chemistry, University of Hamburg, Grindelallee 117, 20146 Hamburg, Germany
2. Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg, Germany
3. Fachbereich Physik, Universität Hamburg, 20355 Hamburg, Germany
4. Fraunhofer Center for Applied Nanotechnology, Grindelallee 117, 20146 Hamburg, Germany