1. Center for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, N-0315 Oslo, Norway
2. Department for Hydrogen Technology, Institute for Energy Technology, P.O. Box 40, NO-2027 Kjeller, Norway
3. Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i, Na Slovance 2, Prague 18221, Czech Republic
4. College of Physics and Electronic Information, Inner Mongolia Normal University, 81 Zhaowuda Road, 010022 Hohhot, China
5. Laboratoire CRISMAT, UMR 6508 CNRS ENSICAEN, 6 bd du Maréchal Juin, 14050 Caen Cedex 4, France