1. National Center for Magnetic Resonance in Wuhan State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences Wuhan 430071 P. R. China
2. University of Chinese Academy of Sciences Beijing 100049 China
3. National High Magnetic Field Laboratory 1800 East Paul Dirac Drive Tallahassee FL 32310-3706 USA