1. CNRS; CRPP, UPR 8641; 33600 Pessac France
2. Univ. Bordeaux, CRPP, UPR 8641; 33600 Pessac France
3. CNRS; ICMCB, UPR 9048; 33608 Pessac Cedex France
4. Univ. Bordeaux, ICMCB, UPR 9048; 33600 Pessac France
5. Present address: DTU Chemistry; Technical University of Denmark; 2800 Kgs. Lyngby Denmark
6. Department of Chemistry; University of Oxford; Oxford OX1 3QR UK
7. Max-Planck Institut für Chemische Energiekonversion; 45470 Mülheim an der Ruhr Germany
8. Institute of General and Inorganic Chemistry; Bulgarian Academy of Sciences; 1123 Sofia Bulgaria
9. ESRF-The European Synchrotron, CS 40220; 38043 Grenoble Cedex 9 France
10. Present address: Faculty of Physics and Center for Nanointegration, Duisburg-Essen (CENIDE); Universität Duisburg-Essen; 47048 Duisburg Germany
11. Department of Chemistry; University of Copenhagen; 2100 Copenhagen Denmark