1. Department of New
Materials and Biosystems, Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, 70569 Stuttgart, Germany
2. Institute of Applied
Physics, Abbe Center of Photonics, Friedrich Schiller Universität Jena, Albert Einstein Straße 15, 07745 Jena, Germany
3. Institute of Theoretical
Solid State Physics, Karlsruhe Institute of Technology, Wolfgang-
Gaede-Str. 1, 76131 Karlsruhe, Germany
4. Institute of Nanotechnology, Karlsruhe Institute of Technology, P.O. Box 3640, 76021 Karlsruhe, Germany
5. Institute of Chemistry, University of Potsdam, Am Mühlenberg 3, 14476 Potsdam OT Golm, Germany