Plasmon-enhanced sensitization of singlet oxygen on silver island films

Abstract

The influence of the plasmonic effect of silver island films on the absorption, fluorescence and long-term luminescence of rose bengal in polyvinyl butyral films has been studied. Under the plasmon effect, the optical density of the dye increased by 3.3 times, the fluorescence intensity by 8.5 times, and the long-lived fluorescence and phosphorescence by 7.08 times and 10.21, respectively. It is shown that in the plasmon field of metal nanoparticles, both an increase in the excitation rate and an increase in the rates of radiative decay of excited singlet and triplet states occur. Phosphorescence of singlet oxygen with a lifetime of 86.46 μs was observed when excited in the absorption band of rose bengal. Based on the calculation of the quenching constants of rose bengal phosphorescence by molecular oxygen molecules, it is shown that the plasmonic effect enhances the energy transfer from dye triplets to oxygen molecules in collision complexes [ТPS…3  g –] as a result of heteroannihilation. Subsequently, the triplet pair decomposes to form a singlet oxygen molecule and a photosensitizer molecule in the ground state. The plasmonic effect of silver nanoparticles leads to an increase in the generation of singlet oxygen by 4.8 times.