作者机构:[1]Department of Physics, Taiyuan Normal University, Taiyuan 030031, China, [2]Department of Physics, Chifeng College, Chifeng 024001, China, [3]China Institute of Atomic Energy, Beijing 102413, China
相关基金:Supported by National Natural Science Foundation of China (10475116, 10535010, 10235030) and National Basic Research Program of China (2007cb815000)