1. Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Photochemistry, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, P. R. China
2. University of Chinese Academy of Science, Beijing 100049, P. R. China
3. Department of Chemistry, University of Akron, Akron, Ohio 44325, United States
4. College of Chemistry, Beijing Normal University, Beijing 100875, P. R. China