Cryogenic Charging and Discharging Kinetics of a Photostimulable Phosphor: Low Charge Rates at Low Temperatures

Abstract

Phosphors that exhibit photostimulated luminescence (PSL), i.e., photostimulable phosphors, possess intrinsic memory. This property has been leveraged historically in optical sensors and imaging devices and more recently toward optical computing. Heretofore, it was unclear whether all-optical PSL effectively manifests at very low temperatures. Herein we characterized the charging and discharging kinetics of an ideal two-level photostimulable phosphor (RbCdF₃:Mn) from ambient to cryogenic temperatures (11 K). While PSL persists at cryogenic temperatures, the charging efficiency decreases significantly. The inhibition is quantitatively described by using an adapted charging model incorporating a weakly bound (31 meV) excitonic state. When the model is extended to include high-temperature thermal ionization effects, the charge/discharge kinetics and the anti-thermal PSL quenching are described with high fidelity. The model can be adapted to describe other photostimulable and persistent phosphors with a luminescent electron donor (e.g., Bi³⁺, Pr³⁺, Cr³⁺, Mn²⁺).