Polyvinyl alcohol–carbon dots composite for UV and 600 keV protons inducing luminescence in air and vacuum

In this paper, carbon dots produced by laser ablation in liquid and incorporated into a polymer foil enable the fabrication of a luminescent sensor in air and vacuum. Polyvinyl alcohol (PVA) containing low-concentration carbon dots (CDs), whose luminescence under UV irradiation is well established. Less investigated is its luminescence effectiveness under irradiation of 600 keV proton beams. While the luminescence induced in the composite polymer by UV at 365 nm is constant, that induced by energetic proton beams decreases with the irradiation time, i.e., with the dose deposited. The proton-induced CDs luminescence, and its decrease in emission intensity during irradiation, could enable real-time sensing of proton detection and radiation damage when incorporated as a coating or functional element within shields, filters, and biomedical devices. PVA+CDs composite could be used for continuous monitoring of cumulative radiation dose via noninvasive luminescence measurements. The observed luminescence quenching acts as a direct optical marker of the damage induced by radiation, offering timely alerts for device maintenance or replacement. This study aims to provide insights into the environment-dependent luminescence response of carbon-dot-based polymer composites, highlighting the distinct roles of air and vacuum conditions, residual gas interactions, and radiation-induced defect formation under UV and proton irradiation.