Radiation-induced changes in the optical properties of NaMgF 3 (Sm): Observation of resettable Sm radio-photoluminescence

Abstract Stable radio-photoluminescence (RPL) is observed in NaMgF 3 (Sm) after X-ray irradiation due to valence conversion of Sm 3+ to Sm 2+ . This valence conversion can be reversed by deep UV (254 nm) illumination. It is likely that this reversible process occurs via defects near some of the Sm 3+ sites that act as hole traps. The ratio of the Sm 2+ /Sm 3+ RPL emissions follows an exponential-type curve dependence on X-ray dose where the ratio saturates above ∼500 Gy. Optically stimulated luminescence (OSL) is also observed but only from Sm 3+ and primarily from electrons trapped at F -centers. The OSL response is demonstrated to be linear up to 100 Gy. Thus, NaMgF 3 (Sm) has potential as a dosimeter where individual irradiations can be monitored via OSL and the total cumulative dose via non-destructive RPL readout. The RPL can be optically reset when required.