1. Department of Physics, Technische Universität München, James-Franck-Str. 1, 85748 Garching, Germany
2. Deutsches Museum, Museumsinsel 1, 80538 Munich, Germany
3. Max Planck Institute for Solid State Research, Heisenbergstrasse 1, 70569 Stuttgart, Germany
4. Institute for Materials Science—Multicomponent Materials, Christian-Albrechts-Universität zu Kiel, Kaiserstr. 2, 24143 Kiel, Germany
5. Nanosystems Initiative Munich and Center for NanoScience, Schellingstrasse 4, 80333 München, Germany
6. Dept. of Chemistry, University of Munich (LMU), Butenandtstraße 5-13, Haus D, 81377 München, Germany
7. Department of Physics, Chemistry and Biology, IFM, Linköping University, 581 83 Linköping, Sweden