1. Department
of Chemistry and Center for NanoScience, Ludwig-Maximilians-University, Butenandtstraße 11, 81377 Munich, Germany
2. Nanosystems Initiative Munich, Schellingstraße
4, 80799 Munich, Germany
3. Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237 Düsseldorf, Germany
4. National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, One Cyclotron Road, Berkeley, California 94720, United States