The effect of gold nanoparticles on exchange processes in collision complexes of triplet and singlet oxygen molecules with excited eosin molecules

We have studied exchange processes in contact complexes of triplet eosin molecules with oxygen molecules in the triplet (3Σg−) and singlet (1Δg) states in thin polyvinylbutyral films in the presence of gold nanoparticles. Upon resonant excitation of surface plasmons in gold nanoparticles into the absorption band of eosin molecules-singlet oxygen sensitizers-we have obtained an increase in the intensity of the delayed fluorescence and an increase in the lifetime of the dye with simultaneous quenching of the luminescence of singlet oxygen. The kinetics of the delayed fluorescence of the dye as a result of singlet-triplet annihilation of triplet eosin molecules with singlet oxygen molecules has been investigated. To compare theoretical and experimental data, we have numerically simulated energy transfer processes. Rate constants of energy transfer and of singlet-triplet annihilation, as well as quenching constants of triplet states of the dye by molecular oxygen, have been calculated. Luminescence quantum yield 1Δg of polyvinylbutyral has been estimated. We have analyzed quantum-chemically electronic mechanisms of singlet-triplet annihilation of oxygen and eosin.