1. Department of Chemistry, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
2. Wigner Research Centre for Physics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest, Hungary
3. Faculty of Physical Sciences, University of Iceland, 107 Reykjavı́k, Iceland
4. Department of Physics, Technical University of Denmark, Fysikvej 307, DK-2800 Kongens Lyngby, Denmark
5. PULSE Institute, SLAC National Accelerator Laboratory, Menlo Park, California 94025, United States