1. Department of Chemistry, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, People's Republic of China, Department of Chemistry, University of Durham, South Road, Durham DH1 3LE, U.K., National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan, and Institut Laue Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble CEDEX 9, France