X-ray absorption near-edge structure of Ag cations in phosphate glasses for radiophotoluminescence applications

Abstract

X-ray absorption near-edge structure (XANES) spectroscopy is one of the most effective techniques for determining the valence states of cations. Since K- and L-edge transition processes are different, the validity of X-ray irradiation to evaluate these excitation processes must be determined. In this study, we focus on the valence states of silver cations in aluminophosphate glasses, whose compositions have been used as radiophotoluminescence (RPL) glass detectors for personal monitoring. Slight difference was observed between the Ag K-edge XANES spectra of reference materials and those of experimental samples. It is also challenging to detect spectral changes due to the coloration of Ag-doped glass. However, absorption edge shifts depending on the valence state were observed in Ag L₃-edge XANES spectra. We found that additional absorption bands, whose peak intensities increase with increasing irradiation doses, were generated at lower absorption energies during the measurement. The degrees of change in absorption intensities depend on the chemical composition of the sample. Considering the nature of the RPL glass detector, we assumed that the species generated are related to the Ag²⁺ species, which is an activator after irradiation.