Variation of index of refraction in the ion-exchanged glasses with the evolution of ionic and neutral silver nano-clustersA. Nahal, A. Jalehdoost, Kh. Hassani and A. FarokhniaeeEur. Phys. J. Appl. Phys., 53 1 (2011) 10701DOI: https://doi.org/10.1051/epjap/2010100075