Affiliation: | 1. Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel (Switzerland), Fax: (+41)?61‐267‐3784;2. Department of Chemistry, University of Basel, St. Johanns‐Ring 19, 4056 Basel (Switzerland), Fax: (+41)?61‐267‐1016;3. Forschungszentrum Karlsruhe GmbH, Institute for Nanotechnology, P.O. Box 3640, 76021 Karlsruhe (Germany) |