1. Institute of Physical Chemistry (IPC) Friedrich Schiller University Jena Helmholtzweg 4 Jena 07743 Germany
2. Leibniz Institute of Photonic Technology (IPHT) Albert‐Einstein‐Str. 9 07745 Jena Germany
3. Adolphe Merkle Institute University of Fribourg Fribourg CH 1700Switzerland
4. Institute of Materials Science Technical University of Darmstadt Alarich‐Weiss‐Strasse 2 Darmstadt D‐64287 Germany