LIU Qiang1**, ZHAO Wan-Xiang1**, ZHENG Cai-Xing2, LIU Sheng-Tao3, WANG Yu-Zhi1**
1. College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China; 2. School of Physics and Electronics, Hunan University, Changsha 410082, China; 3. Educational Science Research Institute, Hunan University, Changsha 410082, China