1. Department of Physics, Technical University of Denmark, Kgs. Lyngby 2800, Denmark
2. Institut für Angewandte Physik, Universität Tübingen, Tübingen 72076, Germany
3. Institute of Physics, Slovak Academy of Sciences, Bratislava 84511, Slovakia
4. Centre of Excellence for Advanced Materials Application, Bratislava 84511, Slovakia
5. Newtec Engineering A/S, Odense M 5230, Denmark
6. Kekulé-Institute for Organic Chemistry and Biochemistry, University of Bonn, Bonn 53121, Germany
7. NanoSYD, Mads Clausen Institute, University of Southern Denmark, Sønderborg 6400, Denmark