1. Department of Chemistry, Iowa State University, Ames, Iowa 50011, United States
2. Ames Laboratory, U.S. Department of Energy, Ames, Iowa 50011, United States
3. Department of Chemistry, University of California at Davis, Davis, California 95616, United States
4. Department of Physics, University of Science and Technology of China, Hefei 230026, China
5. Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, United States