1. Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
2. Institute of Condensed Matter and Nanoscience, Université Catholique de Louvain, Louvain-la-Neuve 1348, Belgium
3. Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599, USA
4. Department of Mechanical Engineering and Materials Science, Duke University, Durham, North Carolina 27708, USA
5. CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China
6. Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, 22761 Hamburg, Germany