STUDY OF SPATIAL CORRELATIONS BETWEEN RADIATION-INDUCED DEFECTS AND THE ACTIVATOR EU-2+ IN THE X-RAY STORAGE PHOSPHOR BAFBREU2+ 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 Eu2+. We 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 Eu2+ 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 angstrom from the Eu2+ activators.