1. Physics Department E20, Technical University of Munich, James-Franck-Strasse 1, 85748 Garching, Germany
2. Department of Physics, Paderborn University, Warburger Strasse 100, 33098 Paderborn, Germany
3. Institutt for Matematikk og Fysikk, University of Stavanger, 4036 Stavanger, Norway
4. Institute of Organic Chemistry, Johannes Kepler University, Altenberger Straße 69, 4040 Linz, Austria