1. Institute for Physical Chemistry and Abbe Centre of Photonics, Friedrich-Schiller-University Jena, Helmholtzweg 4, D-07743 Jena, Germany
2. Institute of Biochemistry and Biophysics, Friedrich-Schiller-University Jena, Philosophenweg 12, D-07743 Jena, Germany
3. Institute of Photonic Technology (IPHT) Jena, Albert-Einstein-Strasse 9, D-07745 Jena, Germany
4. Centre d́Etudes et de Recherches sur les Macromolécules Organiques, Université Joseph Fourier, Centre National de la Recherche Scientifique, Fédération de Recherche en Evolution, 3017, B.P.53, F-38041 Grenoble Cedex 9, France