Photostimulated luminescence in Eu2+-doped fluoroaluminate glasses

Photostimulated luminescence phenomenon was observed in a fluoroaluminate glass doped with ${\mathrm{Eu}}^{\mathrm{2+}}.$ When the x-ray irradiated glass was excited by a He–Ne laser (633 nm), photostimulated luminescence at 400 nm due to the $\text{5d–4f}$ transition of ${\mathrm{Eu}}^{\mathrm{2+}}$ ions was observed. X-ray absorption spectra showed that a part of ${\mathrm{Eu}}^{\mathrm{2+}}$ converted to ${\mathrm{Eu}}^{\mathrm{3+}}$ upon the irradiation of x-ray. By comparing with the investigations on photostimulable luminescence phosphor ${\mathrm{BaFBr:Eu}}^{\mathrm{2+}},$ the luminescence appears to result from the photostimulated recombination of holes and electrons at traps, which leave electrons in a long-lived excited state.