1. Department of Physics and Research Center
OPTIMAS, University of Kaiserslautern, Erwin-Schrödinger-Straße
46, 67663 Kaiserslautern, Germany
2. Graduate School of Excellence Materials Science in Mainz, Erwin
Schroedinger Straße 46, 67663 Kaiserslautern, Germany
3. School of
Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland
4. Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
5. Institute
of Nanotechnology, Karlsruhe Institute of Technology (KIT), D-76344 Eggenstein-Leopoldshafen, Germany
6. Department
of Chemistry and Biochemistry, and Department of Physics, University of Arizona, 1306 E. University Blvd., Tucson, Arizona United States
7. Universite de Strasbourg, Institut de Physique
et de Chimie des Materiaux de Strasbourg, Campus de Cronenbourg, 23 Rue du Loess, 67034 Strasbourg Cedex 2, France
8. I. Physikalisches Institut, Georg-August-Universität Göttingen, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany