1. Beijing National Laboratory for Molecular Sciences; State Key Laboratory for Structural Chemistry of Unstable and Stable Species; College of Chemistry and Molecular Engineering; Peking University; Beijing 100871 P. R. China
2. School of Materials and Energy; Guangdong University of Technology; Guangzhou 510006 P. R. China
3. Institute of Physics; Chinese Academy of Sciences; Beijing 100190 P. R. China
4. Department of Materials Science and Engineering; College of Engineering; Peking University; Beijing 100871 P. R. China