1. Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06520-8114, United States
2. Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States
3. Department of Physics, City College of New York (CCNY), New York, New York 10031, United States
4. Department of Chemistry, The Graduate Center of the City University of New York, New York, New York 10016, United States