1. Surface
Physics and Catalysis, Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
2. Center
for Nano- and Micro technology, Danish Technological Institute (DTI), Gregersenvej, DK-2630 Taastrup, Denmark
3. Center
for Electron Nanoscopy, Department of Physics, Technical University of Denmark, DK-2800 Kgs. Lyngby, Denmark
4. Department
of Materials, Imperial College London, London SW7 2AZ, United Kingdom