1. Institute for Energy Technology, Kjeller NO 2027, Norway, Institute of Nanotechnology, Forschungszentrum Karlsruhe GmbH, P.O. Box 30640, D-76021 Karlsruhe, Germany, Chemistry Department, Moscow State University, Leninskie Gori, Moscow 119992, Russia, and Swiss-Norwegian Beam Line, ESRF, BP 220, F-38043 Grenoble, France