1. Contribution from the Institut für Nanotechnologie, Forschungszentrum Karlsruhe GmbH, PF 3640, D-76021 Karlsruhe, Germany, Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, D-70569 Stuttgart, Germany, Physics Department, King's College London, Strand, London WC2R 2LS, U.K., CNR-INFM DEMOCRITOS National Simulation Center and Center of Excellence for Nanostructured Materials (CENMAT), University of Trieste, Italy, Laboratoire de Chimie Organo-Minérale, Université Louis Pasteur/U.M.R. du...