1. National High Magnetic Field Laboratory, Tallahassee, Florida 32310, United States
2. Department of Biochemistry and Molecular Biology, The Pennsylvania State University, Hershey, Pennsylvania 17033, United States
3. State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, P. R. China
4. Department of Chemical Engineering, University of Puerto Rico, Mayagüez, Puerto Rico 00681
5. Department of Chemistry, The University of North Carolina, Chapel Hill, North Carolina 27599, United States