Photostimulated luminescence in BaX2 : Eu2+ (X=Br, Cl) X-ray storage phosphors

The photostimulated luminescence (PSL) effect in BaX2 :Eu (2+) (X=Br, Cl) is comparable to that observed in BaFBr:Eu2+ which is used in commercial X-ray storage phosphor screens. After X- irradiation the PSL stimulation spectra of BaX2 :Eu (2+) (X=Br, Cl) single crystals are identical to the F centre absorption spectra, i.e. the F centres are the PSL-active electron trap centres. The nature of the hole centres is still unknown. The PSL response time of about 0.70 mus is within experimental error of 0.02 mus identical to the Eu2+ radiative lifetime, whereas in BaCl2 :Eu2+ the PSL response time is 0.60 mus, and thus longer than the Eu2+ radiative lifetime of 0.47 mus