Соllective Fluorescence of Composite Nanoparticles

Abstract

Fluorescence of a suspension of spherical nanoparticles consisting of a gold core surrounded by silicon dioxide doped with fluorescein molecules is experimentally studied. The model of a composite nanoparticle is investigated theoretically and experimentally, taking into account polarization fluctuations. It is shown that a local nonlinear feedback in the system leads to characteristic temperature dependences of the fluorescence linewidth and intensity. As the medium was cooled from room temperature to liquid nitrogen temperature, the fluorescence spectrum narrowed and its intensity strongly increased. A comparison of experimental data with numerical calculations showed that the changes observed in experiments are not explained by the temperature dependence of the parameters of elements of a nanoparticle. The analysis of the dynamics of polarization phases of dye molecules showed that the synergetic effect should be taken into account, which forms the basis of plasmon–polariton superradiance.