1. Centre for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, Gaustadalléen 21, NO-0349 Oslo, Norway
2. Interfaces Traitements Organisation et Dynamique des Systèmes (ITODYS), Université de Paris, 15 Rue Jean-Antoine de Baïf, 75205 Paris, France
3. Centre for Materials Science and Nanotechnology, Department of Physics, University of Oslo, P. O. Box 1048 Blindern, NO-0316 Oslo, Norway