1. Catalan Institute of Nanoscience and Nanotechnology (ICN2)
2. CSIC and The Barcelona Institute of Science and Technology
3. 08193 Barcelona
4. Spain
5. Université de Lyon
6. Université Claude Bernard Lyon 1
7. CNRS
8. IRCELYON - UMR 5256
9. 69626 Villeurbanne Cedex
10. ICREA