Study of spatial correlations between radiation-induced defects and the activator Eu²⁺in the X-ray storage phosphor BaFBr:Eu²⁺with optical detection of electron paramagnetic resonance

For the understanding of the photostimulated emission process of the storage phosphor BaFBr it was assumed that a spatial correlation exists between the F centres and hole centres generated by X-rays and the activator ion Eu 2+ . The authors present direct experimental evidence for such a correlation with the detection of cross-relaxation effects in the optically detected electron paramagnetic resonance. A quantitative analysis of the intensity and spectral shape of the Eu 2+ cross-relaxation spectra is presented. It follows that a substantial fracture of F centres and O - centres (in oxygen-containing BaFBr) are generated with a distance of about 20 AA from the Eu 2+ activators.