1. Department of Physics, Pennsylvania State University, University Park, Pennsylvania 16802, United States
2. Materials Research Institute, Pennsylvania State University, University Park, Pennsylvania 16802, United States
3. School of Physics and Electronics, Qiannan Normal University for Nationalities, Duyun 558000, P.R. China
4. Donostia International Physics Center, Paseo Manuel de Lardizabal 4, 20018 Donostia-San Sebastian, Spain
5. IKERBASQUE, Basque Foundation for Science, Plaza Euskadi 5, 48009 Bilbao, Spain
6. Department of Chemistry and Chemical Biology, Cornell University, Baker Laboratory, Ithaca, New York 14853-1301, United States
7. Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, United States
8. Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States