1. Department of Physics; Technische Universität Kaiserslautern; Erwin-Schrödinger Str. 46, D- 67663 Kaiserslautern Germany
2. Institute of Nanotechnology; Karlsruhe Institute of Technology (KIT); Hermann-von-Helmholtz-Platz 1 76344 Eggenstein-Leopoldshafen Germany
3. Department of Chemistry; Technische Universität Kaiserslautern; Erwin-Schrödinger Str. 52, D- 67663 Kaiserslautern Germany
4. Institute of Inorganic Chemistry; Karlsruhe Institute of Technology (KIT) Engesserstr. 15, D- 76131 Karlsruhe Germany
5. Institute of Physical Chemistry; Karlsruhe Institute of Technology (KIT); Fritz-Haber-Weg 2, D- 76131 Karlsruhe Germany
6. Research Center OPTIMAS; Erwin-Schrödinger Str. 46, D- 67663 Kaiserslautern Germany