1. Center for Free-Electron Laser Science, Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
2. Center for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
3. Department of Physics, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
4. Department of Chemistry, Universität Hamburg, Martin-Luther-King-Platz 6, 20146 Hamburg, Germany
5. LCLS, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
6. European XFEL GmbH, 22869 Schenefeld, Germany
7. Deutsches Elektronen-Synchrotron DESY, 22607 Hamburg, Germany
8. SLAC National Accelerator Laboratory, PULSE Institute, Stanford, California 94305, USA
9. Department of Physics, Stanford University, Stanford, California 94305, USA
10. Department of Chemistry, Aarhus University, 8000 Aarhus C, Denmark
11. J. R. Macdonald Laboratory, Department of Physics, Kansas State University, Manhatten, Kansas 66506, USA
12. Max Planck Institute for Nuclear Physics, 69117 Heidelberg, Germany