1. Department of Applied Physics; Hebrew University of Jerusalem; Jerusalem 91904 Israel
2. Center for Nanoscience and Nanotechnology; Hebrew University of Jerusalem; Jerusalem 91904 Israel
3. Institute of Chemistry; Hebrew University of Jerusalem; Jerusalem 91904 Israel
4. Department of Materials; Imperial College London; London SW7 2AZ UK
5. Laboratory for Multifunctional Materials; Department of Materials; ETH Zurich; Zurich 8093 Switzerland