1. Department of Physics and Astronomy, University of Turku, FI-20014 Turku, Finland
2. Institute of Physics, University of Tartu, W. Ostwaldi 1, EE-50411 Tartu, Estonia
3. Department of Materials Science and Applied Mathematics, Malmö University, SE-20506 Malmö, Sweden
4. Department of Physics, Gothenburg University, Box 100, SE-40530 Gothenburg, Sweden
5. MAX IV Laboratory, Lund University, SE-22100 Lund, Sweden
6. Nano and Molecular Systems Research Unit, University of Oulu, FI-90570 Oulu, Finland