Detection of γ-rays is of vital significance in various areas such as high-energy physics, nuclear medicine, national security, and space exploration. However, many current spectrometry methods are based on ionization effects, which are limited to electron counting and related techniques such as ionization-induced luminescence. Herein, we report an alternative, quantifiable γ-ray chemosensor based on a secondary effect from this ionizing radiation, that is, it was discovered that poly(methyl methacrylate) (PMMA) and polyvinyl chloride (PVC) are more sensitive to a γ-ray-induced acid generation process by surveying a series of commercially available polymers. Accordingly, a pH-sensitive fluorescent quinoline derivative is designed and embedded in PMMA or PVC films, which exhibits dramatic emission shift from blue (λem = 460-480 nm) to red (λem = 570-620 nm) upon exposure to γ-irradiation. A linear response of ratiometric fluorescence intensity (Ired/Iblue) to γ-ray dosage in a wide range (80-4060 Gy) was established, which can be used as a practical visual dosimeter complementary to current techniques.
Keywords: acid generation; pH sensor; radiation chemistry of polymer; ratiometric fluorescence sensing; γ-ray detection.