1. Contribution from the Chemical Sciences Division and Fundamental Sciences Directorate, Pacific Northwest National Laboratory, P.O. Box 999, Richland, Washington 99352, Air Force Research Laboratory, Edwards Air Force Base, California 93524, Loker Hydro-carbon Research Institute, University of Southern California, Los Angeles, California 90089, Department of Chemistry, University of Warwick, Coventry CV4 7AL, West Midlands, U.K., and Department of Chemistry, Spedding Hall, Iowa State University, Ames,...