1. van’t Hoff Institute for Molecular Sciences, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
2. Advanced Research Center for Nanolithography, Science Park 106, 1098 XG Amsterdam, The Netherlands
3. van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
4. Laboratory for Surface Technology and Tribology, Department of Engineering Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands