1. Colorado School of Mines, Department of Chemistry and Geochemistry, 1500 Illinois Street, Golden, Colorado 80401, EAI Corporation, 1308 Continental Drive, Suite J, Abingdon, Maryland 21009, JEOL-USA, Inc., 11 Dearborn Road, Peabody, Massachusetts 01960, and University of Vermont, Department of Physics, Burlington, Vermont 05405-0125