1. Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan
2. Department of Chemistry, National Taiwan University, Taipei 10617, Taiwan
3. National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan
4. Department of Chemical Engineering, National Taiwan University of Science and Technology, Taipei 10607, Taiwan
5. Center of Atomic Initiative for New Materials, National Taiwan University, Taipei 10617, Taiwan