Roles of Near and Far Fields in Plasmon-Enhanced Singlet Oxygen Production

In plasmon-enhanced singlet oxygen (O-1(2)) production, irradiation of a hybrid photosensitizer metal nanoparticle leads to a significant alteration of the photosensitizer's O-1(2) 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 O-1(2) production using a tunable model nanoplatform, Rose Bengal-decorated silica coated metal nanoparticles. By correlating (1)O(2)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 O-1(2) 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.