1. Chair of Physical Chemistry, Department of Chemistry & Catalysis Research Center, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany
2. Nanosystems Initiative
Munich, Schellingstrasse 4, 80799 München, Germany
3. Walter
Schottky Institute and Physics Department, Technische Universität München, Am Coulombwall 4, 85748 Garching, Germany