The effect of ionizing radiation on the optical properties of NaMgF3(Mn): Observation of an F-center Mn complex

We report the results from optical absorption, photoluminescence, radioluminescence, and optically stimulated luminescence measurements on polycrystalline NaMgF3(Mn). A point defect that absorbed near 340 nm at 300 K was observed after X-ray irradiation, which is not seen in the pure compound and may be due to self-trapped holes close to the Mn sites. This defect could be optically bleached, and optically stimulated luminescence was observed during the bleaching process. Non-distorted and distorted Mn2+ photoluminescence was found where only the non-distorted sites showed optically stimulated luminescence. Both sites displayed radioluminescence, but the dependence on the radiation dose was different for each site. An F-center Mn complex was observed after X-ray irradiation, which has not been previously reported for the NaMgF3(Mn) compound. The photoluminescence emission at 670 nm from this complex increased with increasing radiation dose and was not bleached by optical excitation at 566 nm. However, it could be bleached after 254 nm excitation. Thus, unlike Mn2+ optically stimulated luminescence, the photoluminescence from this emission can be used to provide a non-destructive measure of the radiation dose. Our results show that NaMgF3(Mn) can potentially be used as a radiation dosimeter for dose-rate monitoring via radioluminescence, continual monitoring of individual doses via F-center Mn complex photoluminescence, and cumulative dose detection via optically stimulated luminescence.