1. Center
for Nanochemistry, 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, People’s Republic of China
2. Institute
of Physics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
3. Department
of Materials Science and Engineering, College of Engineering, Peking University, Beijing 100871, People’s Republic of China