1. Departments of Chemistry and Physics, University of California, Berkeley, California 94720
2. School of Chemistry, University of Wollongong, Wollongong, New South Wales 2522, Australia
3. Department of Chemistry, University of Wisconsin—Washington County, West Bend, Wisconsin 53095
4. Combustion Research Facility, Mail Stop 9055, Sandia National Laboratories, Livermore, California 94551-0969
5. Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720
6. Departments of Chemistry and Physics, University of California, Berkeley, California 94720 and Chemical Sciences Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720