1. Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
2. Department of Physics and Astronomy, University of Uppsala, SE-75120 Uppsala, Sweden
3. Institute of Physics, University of Tartu, W. Ostwald 1, EST-50411, Tartu, Estonia
4. Department of Chemistry – BMC, University of Uppsala, SE-75123 Uppsala, Sweden
5. Center for Free-Electron Laser Science, DESY, DE-22607 Hamburg, Germany