1. Department of Chemistry, University of Colorado, Boulder, CO 80309-0215, USA.
2. General Atomics Electromagnetic Systems Group (GA-EMS), 6685 Gunpark Dr. #230, Boulder, CO 80301, USA.
3. U.S. Naval Research Laboratory, 4555 Overlook Ave., SW, Washington, DC 20375, USA.
4. Nanochemistry Department, Italian Institute of Technology, via Morego 30, Genova, GE, 16163, Italy.
5. Department of Chemistry, Columbia University, New York, NY 10027, USA.