1. Federal Institute for Materials Research and Testing (BAM), Division Biophotonics, Richard-Willstätter-Str. 11, D-12489 Berlin, Germany
2. Department of Physics, Humboldt-Universität zu Berlin, Newtonstr. 15, D-12489 Berlin, Germany
3. Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, D-12489 Berlin, Germany
4. PolyAn GmbH, Rudolf-Baschant-Str. 2, D-13086 Berlin, Germany