[1] Leibniz Inst Photon Technol, Albert Einstein Str 9, D-07745 Jena, Germany
[2] Friedrich Schiller Univ Jena, Inst Phys Chem, D-07745 Jena, Germany
[3] Friedrich Schiller Univ Jena, Abbe Ctr Photon, D-07745 Jena, Germany
[4] Univ Bielefeld, Dept Phys, Biomol Photon, Univ Str 25, D-33615 Bielefeld, Germany
[5] Univ Calif Davis, Dept Internal Med, Sacramento, CA 95817 USA
[6] Univ Calif Davis, NSF Ctr Biophoton, Sacramento, CA 95817 USA