1. Lehrstuhl für Experimentalphysik 1 and Augsburg Centre for Innovative Technologies (ACIT), Universität Augsburg, Universitätsstr. 1, 86159 Augsburg, Germany
2. Nanosystems Initiative Munich (NIM), Schellingstr. 4, 80799 München, Germany
3. Chemistry Department and Materials Science & Engineering Program, University of California, Riverside, California 92521, USA
4. Department of Physics, Pepperdine University, Malibu, California 90263, USA