1. Contribution from the Key Laboratory of Organic Solids, Beijing National Laboratory for Molecular Sciences (BNLMS), Institute of Chemistry, Chinese Academy of Sciences, 100080 Beijing, P. R. China, and Department of Chemistry, Beijing Normal University, 100875 Beijing, P. R. China, State Key Laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, 100080 Beijing, P. R. China