1. Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, U.K.
2. Department of Physics, University of Ottawa, 150 Louis Pasteur Pvt, Ottawa, ON K1N 6N5, Canada
3. Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States
4. National Research Council of Canada, Ottawa, ON K1A 0R6, Canada
5. Department of Chemistry, University of Copenhagen, 2100 Copenhagen ø, Denmark
6. Department of Chemistry and Biomolecular Sciences, University of Ottawa, 150 Louis Pasteur Pvt, Ottawa, ON K1N 6N5, Canada
7. Joint Centre for Extreme Photonics, University of Ottawa - National Research Council, Ottawa, ON K1N 5A2, Canada