1. Key Laboratory of Functional Materials Physics
and Chemistry, Jilin Normal University, Ministry of Education, Siping 136000, P. R. China
2. Huaibei Normal University, Huaibei 235000, P. R. China
3. Changchun
Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033, P. R. China
4. University of Chinese Academy of Sciences, Beijing 100039, P. R. China