1. Department of Chemistry, Huazhong University of Science and Technology, Wuhan 430074, China, Key Laboratory of Cellulose and Lignocellulosics Chemistry, Guangzhou Institute of Chemistry, Chinese Academy of Sciences, P.O. Box 1122, Guangzhou Leyiju, China, Department of Physics, Wuhan University, Wuhan 430072, China, and State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China