1. Department of Chemistry Georgetown University 37th and O Streets NW Washington, D.C. 20057 United States
2. P. Roy and Diana T. Vagelos Laboratories Department of Chemistry University of Pennsylvania 231 S. 34th Street Philadelphia Pennsylvania 19104 United States
3. Los Alamos National Laboratory Los Alamos New Mexico 87545 United States
4. Department of Chemistry and Biochemistry Florida State University Tallahassee Florida 32306 United States