1. Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
2. Department of Physics and Astronomy, University of Southern California, Los Angeles, California 90089, United States
3. Weapons and Materials Research Directorate, U.S. Army Research Laboratory, Aberdeen Proving Ground, Aberdeen, Maryland 21005, United States
4. Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58108, United States