1. Max Planck Institute for the Structure and Dynamics of Matter, Bldg. 99 (CFEL), Luruper Chaussee 149, 22761 Hamburg, Germany
2. Hamburg Centre for Ultrafast Imaging (CUI), Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
3. Department of Chemistry and Physics, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada
4. Department of Physics, Chemistry and Biology (IFM), Linköping University, 581 83 Linköping, Sweden