1. Department of Chemistry, McMaster University, Hamilton, Ontario, Canada, L8S 4M1, Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, California 91420, Center for Materials Research and Analysis, Department of Physics, University of NebraskaLincoln, Lincoln, Nebraska 68588-0111, Institut für Physik, Johannes Gutenberg-Universität Mainz, D-55099 Mainz, Germany, Institute for Molecular Science, Myodaiji, Okazaki 444, Japan, and W. M. Keck Center for Molecular Electronics and the Department of...