[1] Department of Chemistry, University of California, Berkeley, CA 94720, United States
[2] Department of Physics, University of California, Berkeley, CA 94720, United States
[3] Department of Mathematics, University of California, Berkeley, CA 94720, United States
[4] Ecl. Natl. Sup. des Telecom., Paris, France
[5] Chemistry Department, University of Toronto, 80 St. George Street, Toronto, Ont. M5S 3H6, Canada