1. Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy, Max Born Strasse 2A, 12489 Berlin, Germany
2. Institute for Methods and Instrumentation for Synchrotron Radiation Research, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
3. Institute for Nanostructure and Solid State Physics, Center for Free-Electron Laser Science, Luruper Chaussee 149, 22761 Hamburg, Germany
4. Department of Physics, AlbaNova University Center, Stockholm University, 106 91 Stockholm, Sweden