* Corresponding authors

^a Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustraße 3, Berlin, Germany
E-mail: siegfried.eigler@fu-berlin.de

^b Chamlers University of Technology, Gothenburg, Sweden

^c Bundesanstalt für Materialforschung und-prüfung (BAM), Department 1, Division Biophotonics, Richard Willstätter Straße 11, Berlin, Germany
E-mail: ute.resch@bam.de

^d Institute of Chemistry and Biochemistry, Freie Universität Berlin, Fabeckstraße 34-36, Berlin, Germany