[1] Stt. Key Lab. Magnetic Reson. A., Wuhan Inst. of Phys. and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
[2] Laser Spectroscopy Laboratory, Anhui Inst. Opt. and Fine Mechanics, Chinese Academy of Sciences, Hefei 230031, China
[3] Department of Physics, Liaocheng Teachers University, Liaocheng 252059, China
[4] Department of Physics, Hubei Normal University, Huangshi 435002, China