In plasmon-enhanced singlet oxygen (1O2) production, irradiation of a hybrid photosensitizer–metal nanoparticle leads to a significant alteration of the photosensitizer’s 1O2 yield. The quest for a more rational design of these nanomaterials calls for a better understanding of the enhancement mechanism that, to this day, remains largely unexplored. Herein, we introduce a new methodology to distinguish the near- and far-field contributions to the plasmon-enhanced 1O2 production using a tunable model nanoplatform, Rose Bengal-decorated silica-coated metal nanoparticles. By correlating 1O2 production to the experimental and simulated optical properties of our nanoparticles, we effectively discriminate how the near- and far-field effects contribute to the plasmonic interactions. We show that these effects work in synergy; i.e., for nanoparticles with a similar local field, the production of 1O2 correlates with maximized scattering yields. Our results expound the critical plasmonic aspects in terms of near and far fields for the design of an efficient hybrid plasmonic nanoparticle photosensitizer.
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