1. State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, National Center for Magnetic Resonance in Wuhan, 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. Department of Chemistry, City University of Hong Kong, Kowloon, Hong Kong 999077, P. R. China