1. Stanford PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
2. Department of Applied Physics, Stanford University, Stanford, California 94305, United States
3. Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
4. Chemistry Research Laboratory, Department of Chemistry, University of Oxford, Oxford OX1 3TA, U.K.
5. National Research Council Canada, Ottawa, Ontario K1A 0R6, Canada
6. Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany
7. Department of Physics, Stanford University, Stanford, California 94305, United States
8. Daresbury Laboratory, Daresbury, Warrington, Cheshire WA4 4AD, U.K.
9. Institut für Physik, Universität Kassel, Heinrich-Plett-Straße 40, 34132 Kassel, Germany
10. School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, U.K.
11. Max-Born-Institute, Max-Born-Straße 2A, 12489 Berlin, Germany
12. J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhattan, Kansas 66506, United States
13. Department of Physics, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
14. Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
15. NRC-uOttawa Joint Centre for Extreme Photonics, Ottawa, Ontario K1A 0R6, Canada