1. University of Basel, Department of Chemistry, Klingelbergstrasse 80, 4056 Basel, Switzerland
2. University of Basel, Swiss Nanoscience Institute, Klingelbergstrasse 82, 4056 Basel, Switzerland
3. Swiss Federal Laboratories for Materials Testing and Research (Empa), Nanoscale Materials Science, Überlandstrasse 129, 8600 Dübendorf, Switzerland