1. Inorganic Chemistry and Catalysis group Department of Chemistry Utrecht University Universiteitsweg 99 3584 CG Utrecht The Netherlands
2. Department of Physics University of Helsinki P. O. Box 64 00014 Helsinki Finland
3. Laboratory of Inorganic Chemistry Department of Chemistry ETH Zürich Vladimir-Prelog-Weg 1 8093 Zürich Switzerland
4. Department of Physics Center for Materials Science and Nanotechnology University of Oslo P.O. Box 1048 0316 Oslo Norway
5. Department of Chemistry University of Oslo P.O. Box 1033 0315 Oslo Norway