1. Department of Physics, Korea University, Seoul 02841, Republic of Korea
2. Department of Physics, Chungbuk National University, Cheongju 28644, Republic of Korea
3. KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Republic of Korea
4. Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801, United States
5. Department of Integrative Energy Engineering, Korea University, Seoul 02841, Republic of Korea
6. Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Champaign, Illinois 61801, United States
7. Center for Molecular Spectroscopy and Dynamics, Institute for Basic Science, Seoul 02841, Republic of Korea