1. Institute for Physical Chemistry (IPC) and Abbe Center of Photonics Friedrich Schiller University Jena Helmholtzweg 4 07743 Jena Germany
2. Present address: DS Deutschland GmbH Am Kabellager 11–13 51063 Cologne Germany
3. Institute of Chemistry and Bioengineering Technical University Ilmenau Weimarer Str. 32 98693 Ilmenau Germany