1. Competence Centre for Catalysis, Chalmers University of Technology, SE-412 96, Göteborg, Sweden
2. ESRF, 6 rue Jules Horowitz -38000 Grenoble, France
3. Division of Synchrotron Radiation Research, Lund University, Box 118, SE-221 00, Sweden
4. Kamerlingh Onnes Laboratory, Leiden University, P.O. Box 9504, 2300 RA Leiden, The Netherlands