1. Department of Photonics Engineering, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
2. Center for Electron Nanoscopy, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
3. Both authors contributed equally.
4. Center for Nanostructured Graphene (CNG), Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
5. Department of Micro and Nanotechnology, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark