1. Saarland University, Theoretical Physics and Center for Biophysics, Campus E2 6, 66123 Saarbrücken, Germany
2. Institute for Microbiology and Genetics, Georg-August-Universität Göttingen, Justus-von-Liebig Weg 11, 37077 Göttingen, Germany
3. Synchrotron Soleil, Beamline SWING, Saint Aubin BP48, F-91192 Gif Sur Yvette Cedex, France