1. National Center for Magnetic Resonance in Wuhan State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Key Laboratory of Magnetic Resonance in Biological Systems 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 P. R. China
3. Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan 430074 P. R. China