1. Department of Physics and Institute for Polymers and Organic Solids, Department of Chemistry and Biochemistry, and Program in BioMolecular Science and Engineering, University of California, Santa Barbara, California 93106 and Division of Biological Inorganic Chemistry, Key Laboratory of Rare Earth Chemistry and Physics, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, Jilin 130022, China