1. Department of Chemistry, University of Arizona, Tucson, Arizona 86721 (R.P.S., A.K.K., M.B.D.); Sandia National Laboratories, Albuquerque, New Mexico 87185 (C.A.G.); Pacific Northwest National Laboratories, Richland, Washington 99352 (D.W.K.); and Department of Chemistry, Indiana University, Bloomington, Indiana 47405 (G.M.H.)