1. College of Chemistry and Chemical Engineering; Shaoxing University; Shaoxing 312000 China
2. Department of Chemistry; University of Tennessee; Knoxville TN 37996 USA
3. Wuhan Center for Magnetic Resonance; State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics; Wuhan Institute of Physics and Mathematics; Wuhan 430071 China
4. Chemical Sciences Division; Oak Ridge National Laboratory; Oak Ridge TN 37831 USA