1. Department of Physics and Astronomy, University of California, Irvine, California 92697, Department of Physics and Astronomy, Rutgers University, 136 Frelinghuysen Road, Piscataway, New Jersey 08854, Department of Chemistry, Princeton University, Washington Road, Princeton, New Jersey 08544, Department of Chemistry, Purdue University, West Lafayette, Indiana 47907, and Department of Chemistry, University of California, Irvine, California 92697