1. Peter A. Rock Thermochemistry Laboratory and NEAT ORU, University of California at Davis, Davis, California 95616, Intense Pulsed Neutron Source Division, Argonne National Laboratory, Argonne, Illinois 60439, Department of Geological Sciences, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, and Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah 84602