Mechanism of Photostimulated Luminescence Process in BaFBr:Eu2+Phosphors

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Abstract
The formation of photostimulated luminescence (PSL) centers in BaFBr:Eu2+single-crystal phosphors is studied in the 5–9 eV vacuum ultraviolet region. The centers are efficiently formed by the Eu2+photoionization absorption at 6.6 eV. The PSL excitation spectrum after the photoionization excitation is almost the same as that after X-ray excitation. Photoconductivity is generated in the PSL process after the photoionization excitation. These results present further confirmation of the PSL mechanism of Takahashiet al.. [J. Lumin. 31 & 32 (1984) 266]. The numerical analysis of the dependence of the PSL intensity on X-ray excitation intensity, assuming bimolecular kinetics in accord with this mechanism, gives the linear dependence over a very wide range of X-ray intensity under the practical conditions in the PSL applications. Thus the mechanism of Takahashiet al.. is definitely established.