1. Contribution from the Department of Chemistry, Emory University, Atlanta, Georgia 30322, Intense Pulsed Neutron Source, Argonne National Laboratory, Argonne, Illinois 60439, Department of Chemistry and Stanford Synchrotron Radiation Laboratory, Stanford University, Stanford, California 94305, Department of Chemistry and Chemical Biology, The University of New Mexico, Albuquerque, New Mexico 87131−0001, Ames Laboratory, Iowa State University, Ames, Iowa 50011, Cherry L. Emerson Center for Scientific...