1. Department of Energy Conversion and Storage, Technical University of Denmark, Frederiksborgvej 399, 4000 Roskilde, Denmark
2. Center for Free-Electron Laser Science, DESY, Notkestrasse 85, 22607 Hamburg, Germany
3. The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany
4. Department of Physics, Universität Hamburg, Jungiusstrasse 9, 20355 Hamburg, Germany