1. Physics Department, University of Wisconsin, Milwaukee, WI 53211, USA.
2. Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA.
3. Department of Physics, Arizona State University, Tempe, AZ 85287, USA.
4. Linac Coherent Light Source, SLAC National Accelerator Laboratory, Sand Hill Road, Menlo Park, CA 94025, USA.
5. Lawrence Livermore National Laboratory, Livermore, CA 94550, USA.
6. Centre for Ultrafast Imaging, University of Hamburg, 22761 Hamburg, Germany.
7. Center for Free Electron Laser Science, Deutsches Elektronen Synchrotron DESY, Notkestrasse 85, 22607 Hamburg, Germany.
8. Hauptman-Woodward Institute, State University of New York at Buffalo, 700 Ellicott Street, Buffalo, NY 14203, USA.
9. Center for Advanced Radiation Sources, University of Chicago, Chicago, IL 60637, USA.
10. Department of Biochemistry and Molecular Biology and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA.
11. Faculty of Natural Sciences, Life Sciences, Imperial College, London SW7 2AZ, UK.