1. Department of Chemistry and Biochemistry, 0300 Old Main Hill, Utah State University, Logan, Utah 84322-0300, Department of Physics, 2710 University Drive, Washington State University, Richland, Washington 99354, and W. R. Wiley Environmental Molecular Sciences Laboratory and Chemical Sciences Division, Pacific Northwest National Laboratory, MS K8-88, P.O. Box 999, Richland, Washington 99352