1. Faculty of Mathematics and Natural Sciences, Department of Chemistry, Tübingen University, 72076 Tübingen (Germany)
2. Department of Materials, ETH Zurich, Wolfgang Pauli Strasse 10, 8093 Zurich (Switzerland)
3. Present address: Harvard University, School of Engineering and Applied Science, 29 Oxford St., Cambridge, MA 02138 (USA)
4. Institute for Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), Kaiserstrasse 12, 76128 Karlsruhe (Germany)
5. ESRF, BP220, 6 rue Jules Horowitz, 38043 Grenoble (France)