Benzoic Acid–Polymer Composites as Radiophotoluminescent Materials for X-Ray Dosimetry

Abstract Solid-state radiophotoluminescence (RPL) dosimeters based on organic materials were developed. Focusing on the generation of fluorescent molecules from the reaction between benzoic acid in polymers and radicals, samples of PMMA, PVC, and PVA containing benzoic acid at different concentrations were prepared. The responses of these samples were evaluated by measuring the photoluminescence spectra before and after X-ray irradiation. In the PVA samples before and after X-ray irradiation, the emission peak was observed at 412 nm and is attributed to salicylic acid. The photoluminescence intensity increased upon X-ray irradiation. Based on the FT-IR spectra of the samples, the increase in the photoluminescence intensity after X-ray irradiation is attributed to the formation of salicylic acid. At the optimal benzoic acid concentration of 1 wt%, the linear response range was 0–60 Gy. In the PMMA samples before and after X-ray irradiation, the emission peak was observed at 435 nm and is attributed to benzoic acid tetramers. The photoluminescence intensity increased upon X-ray irradiation. Based on the FT-IR spectra of the samples, the increase in the photoluminescence intensity is attributed to an increase in the photoluminescence efficiency of benzoic acid tetramers resulting from PMMA oxidation. At the optimal benzoic acid concentration of 1 wt%, the linear response range was 0–100 Gy. In the PVC samples before and after X-ray irradiation, the emission peak was observed at 437 nm and is attributed to benzoic acid tetramers. The photoluminescence intensity decreased upon X-ray irradiation. Based on the FT-IR spectra of the samples, the decrease in the photoluminescence intensity is attributed to the decomposition of benzoic acid tetramers. The radiation-induced reactions in the PMMA and PVA samples can potentially be utilized as the operating principle for organic RPL dosimeters.