Interplaying the Photoredox Behavior of Dopants in Luminescent Materials for Two-Dimensional Radiation Dosimetry

Accurate multidimensional radiation dosimetry is crucial for guaranteeing irradiation effects and minimizing negative effects across various fields, while it remains a critical bottleneck for existing dosimetry methods. Here, an approach of using the irradiation dose-dependent photoreduction behavior of Eu3+ to Eu2+ in NaCa1-xEuxPO4 phosphor was presented for two-dimensional radiation dosimetry. Systematic spectroscopy characterization reveals that the photoredox behavior of Eu3+↔Eu2+ can be reasonably interpreted using the local electron transfer model. Upon irradiation, the dose information is encoded into the photoluminescence intensities of Eu in its different valence states, leading to a dose-dependent luminescence color change from red to green. This characteristic enables the determination of spatial dose distribution through the ratio of green to red pixel intensities from the captured digital photographs, eliminating the cumbersome process of point-by-point reading required by traditional luminescence dosimeters. As a proof of concept, NaCa0.999Eu0.001PO4 is utilized for two-dimensional radiation dosimetry. The spatial dose distribution information can be readily obtained by taking photos upon UV illumination and the dose information can be well maintained for over 36 h. This work not only offers an approach for two-dimensional radiation dosimetry but also provides deeper insights into the mechanism underlying photo-induced electron transfer processes in phosphors.