1. Department
of Chemistry, Durham University, South Road, Durham, DH1 3LE U.K.
2. Department
of Chemistry, Duke University, Durham, North Carolina 27708 United States
3. Department of Physics, North Carolina A&T State University, Greensboro, North Carolina 27411 United States
4. Department
of Chemistry and Quantum Theory Group, Tulane University, New Orleans, Louisiana 70118 United States