Evidence of transient species occurring in the reduction process of trivalent lanthanides under 2.5 MeV electron irradiation by in situ cathodoluminescence and time-resolved photoluminescence

In situ cathodoluminescence and time-resolved photoluminescence measurements were carried out on Sm-doped glasses during a 2.5 MeV electron irradiation. These experiments allow characterizing more precisely the mechanisms operating under irradiation and more specifically the reduction processes of Sm(3+) to Sm(2+) ions. Sm(2+) emission lines appear in the first steps of the irradiation, however, the (5)D(0) -> (7)F(0-2) emission lines of Sm(2+) were not observed on the cathodoluminescence spectrum. Moreover, two sites of Sm2+ have been evidenced in the glasses; the formation of each species is clearly different. Relaxation processes of Sm(3+) and Sm(2+) leads to consider the existence of different transient states of Sm(3+) and Sm(2+) species which are annealed after irradiation. We propose some synthetic schemes of the reduction mechanisms produced during the irradiation. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3125513]