1. Contribution from the Department of Chemistry, University of California, Berkeley, California 94720, Chemical and Environmental Sciences Laboratory, General Motors Corporation, Warren, Michigan 48090, College of Engineering, Purdue University, West Lafayette, Indiana 47907, Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, Department of Materials Science and Engineering, University of Maryland, College Park, Maryland 20742, and Indiana University...