1. Nuclear Materials Technology (NMT-16), Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545, Department of Chemistry, The Pennsylvania State University, 104 Chemistry Building, University Park, Pennsylvania 16802, and Materials Science and Technology (MST-8), Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, New Mexico 87545