Optically reversible Tm3+ → Tm2+ radiophotoluminescence in NaMgF3:Tm

• Published in: Optical materials 2022-11, Vol.133, p.112926, Article 112926
• Main Authors: Schuyt, J.J., Williams, G.V.M., Chong, S.V.
• Format: Article
• Language: English
• Subjects: NaMgF3; Optically stimulated luminescence; Radiophotoluminescence; Thulium; Tm2
• ISSN: 0925-3467; 1873-1252
• DOI: 10.1016/j.optmat.2022.112926

Infrared radiophotoluminescence was observed in NaMgF3:Tm from the X-ray-induced reduction of Tm3+ → Tm2+. The 4f13(2F5/2) → 4f13(2F7/2) Tm2+ emission only appeared after irradiation and peaked at 1130 nm where the emission energy was compressed by a factor of 1.15 times relative to isoelectronic Yb3+ in NaMgF3:Yb. The Tm2+ emission intensity increased monotonically with absorbed dose up to at least 360 Gy and the integrated intensity increased linearly up to at least 60 Gy. The Tm2+ photoluminescence could be probed non-destructively by exciting into the peak of the lowest energy 4f13 → 4f125d1 band at 450 nm, and destructively probed using stimulation at 280 nm, whereupon the photo-induced oxidation Tm2+ → Tm3+ occurred. Additionally, Tm3+ optically stimulated luminescence was observed after irradiation when stimulating into the F-centre absorption band at 340 nm. The optically reversible radiophotoluminescence and optically stimulated luminescence phenomena have potential applications in radiation dose monitoring and optical information storage. •Photoluminescence and radiophotoluminescence of Tm-doped NaMgF3 is presented.•The X-ray induced reduction Tm3+ .→ Tm2+ was observed via radiophotoluminescence•The Tm2+ emission intensity increased with total X-ray dose.•Tm2+ radiophotoluminescence could be non-destructively probed via 4f125d1 excitation.