1. Centre
for Materials Science and Nanotechnology, Department of Chemistry, University of Oslo, P.O.
Box 1033, Blindern, Oslo N-0315, Norway
2. Department
of Physics, University of Liverpool, Liverpool L69 7ZE, United Kingdom
3. Institute for Energy Technology, Kjeller, N-2007, Norway
4. Department
of Chemistry, University of Liverpool, Liverpool L69 7ZD, United Kingdom