1. European XFEL GmbH, Holzkoppel 4, 22869 Schenefeld, Germany
2. Division of Theoretical Chemistry & Biology, KTH Royal Institute of Technology, SE-10691 Stockholm, Sweden
3. State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China
4. Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China
5. Yangtze Delta Institute of Optoelectronics, Peking University Nantong, Jiangsu 226010, China
6. Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, U.K.
7. Department of Physics, School of Physical Science & Technology, Ningbo University, Ningbo 315211, P. R. China
8. Departments of Chemistry & Physics, University of Toronto, Toronto M5S 3H6, Canada
9. Rosalind Franklin Institute, Harwell, Oxfordshire OX11 0QX, U.K.
10. Department of Pharmacology, University of Oxford, Oxford OX1 3QT, U.K.