Characterisation and unique behaviours of radiophotoluminescence Ag-activated phosphate glass under high-dose gamma and high-LET particle irradiation

We investigated the optical properties and unique behaviours of radiophotoluminescence (RPL) centres in Ag-activated phosphate glass subjected to a high dose of ⁶⁰Co gamma ray irradiation. Using the absorbance-transmittance excitation-emission matrix technique, we obtained a corrected three-dimensional (3D) matrix that represents the true excitation and emission spectra. Additionally, a similar trend was observed in the dose-dependence of the orange-to-blue RPL intensity ratio for high doses of low linear energy transfer (LET) radiation (in this work) and high LET radiation, such as alpha particles and heavy charged particles (HCPs). However, it was characterised by a rapid decline in orange RPL efficiency (known as ‘LET quenching’). Moreover, we analysed the fluorescence lifetimes and spectra of the components, as observed in the steady-state emission. By tracking the changes in the RPL intensity, fluorescence lifetimes, and peak wavelength shifts as a function of gamma ray dose, we discovered for the first time that blue, green, orange, red, and near-infrared RPL exhibit complex behaviours, such as reduction, enhancement, disappearance, and emergence, while preserving their spectral profiles. We aimed to explore whether Ag-activated phosphate glass could serve as both a dosimeter and tool for evaluating LET values.