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 Sm³⁺ to Sm²⁺ ions. Sm²⁺ emission lines appear in the first steps of the irradiation, however, the ⁵D₀→ ⁷F_0-2 emission lines of Sm²⁺ 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 Sm³⁺ and Sm²⁺ leads to consider the existence of different transient states of Sm³⁺ and Sm²⁺ species which are annealed after irradiation. We propose some synthetic schemes of the reduction mechanisms produced during the irradiation.