1. Department of Chemistry, University of Manchester, Manchester M13 9PL, U.K.
2. College of Chemistry and Molecular Engineering, Beijing National Laboratory for Molecular Sciences, Peking University, Beijing 100871, China
3. College of Chemistry, Beijing Normal University, Beijing 100875, China
4. The European Synchrotron Radiation Facility, 71 Avenue des Martyrs CS40220 Grenoble Cedex 9 38043, France