1. Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena 91125, California, United States
2. Department of Physics, Tamkang University, New Taipei City 251301, Taiwan
3. Department of Chemistry, National Taiwan University and Advanced Research Center for Green Materials Science and Technology, Taipei 10617, Taiwan
4. Department of Chemical Engineering, University of Massachusetts Amherst, Amherst 01003−9303, Massachusetts, United States