[1] Univ Munich LMU, Dept Chem, Butenandtstr 11 E, D-81377 Munich, Germany
[2] Univ Munich LMU, Ctr NanoSci CeNS, Butenandtstr 11 E, D-81377 Munich, Germany
[3] BAM Fed Inst Mat Res & Testing, Div Biophoton 1 2, Richard Willstaetter Str 11, D-12489 Berlin, Germany
[4] Bielefeld Univ, Fac Chem, Univ Str 25, D-33615 Bielefeld, Germany
[5] Bielefeld Univ, Ctr Mol Mat CM2, Univ Str 25, D-33615 Bielefeld, Germany
[6] Univ Lincoln, Sch Chem, Joseph Banks Labs, Lincoln LN6 7TS, England