1. Centro de Investigação em Química
2. Department of Chemistry and Biochemistry
3. Faculty of Science
4. University of Porto
5. 4169-007 Porto
6. Laboratoire de Physique des Solides
7. CNRS UMR8502 and Univ. Paris-Sud
8. Université Paris-Saclay
9. 91405 Orsay Cedex
10. France
11. Laboratoire Léon Brillouin
12. CEA Saclay
13. 91191 Gif sur Yvette Cedex