1. Bionanotechnology and Nanomedicine Laboratory, Department of Chemistry and Nano-science Center, University of Copenhagen, Universitetsparken 5, DK-2100, Copenhagen, Denmark
2. Nano-science Center and Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100, Copenhagen, Denmark
3. Institut de Science des Matériaux de Mulhouse
(IS2M), CNRS UMR7361, Université de Haute-Alsace,15,
rue Jean Starky, BP 2488, F-68057 Mulhouse cedex, France