1. Contribution from the Department of Materials and Interfaces, The Weizmann Institute of Science, 76100-Rehovot, Israel, Chemical Research Support, The Weizmann Institute of Science, 76100-Rehovot, Israel, Hasylab at DESY, Notkestrasse 85, D-22607 Hamburg, Germany, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark, Department of Physics and London Centre for Nanotechnology, University College, Gower Street, London WC1E 6BT, England, and Centre for...