Gamma-irradiation induced nonconventional fluorescence enhancement in silicone foams

An unexpected fluorescence enhancement phenomenon in silicone foams induced by gamma-irradiation is reported. These materials contain no traditional luminophores. The fluorescence intensity increases with the absorbed dose (within 1000 Gy). Time-dependent density functional theory (TDDFT) calculations suggest that the mechanism is a crosslinking-enabled emission process, which is enhanced by gamma-irradiation. The fluorescence changes are visible and can even applied to distinguish irradiated silicone foam samples with absorbed doses less than 25 Gy, achieving sensitive visualization of gamma-irradiation damage. The potential applications for radiation damage self-reporting and information encryption are demonstrated. The fluorescence intensity shows similar trends with radiolysis gas products (typical aging parameter) in early-stage irradiation, which can represent radiation-induced crosslinking and radiolysis respectively to reveal the changes of materials after low dose irradiation from two aspects. This work could broaden the application of nonconventional fluorescent materials and help understand the effects of low-dose radiation on silicone materials.