1. Department of Physics and Center for Hybrid Nanostructure (CHyN), Universität Hamburg, Luruper Chaussee 149, Hamburg, 22761 Hamburg, Germany
2. Department of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52074 Aachen, Germany
3. Institut für Nanostrukturforschung, Center for Free Electron Laser Science (CFEL), Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
4. Department of Technical Chemistry I, Universität Duisburg-Essen and Center for Nanointegration Duisburg-Essen (CENIDE), 45141 Essen, Germany
5. Department of Chemistry, Universität Hamburg, Grindelallee 117, 20146 Hamburg, Germany