Nonradiative Energy Migration in Spherical Nanoparticles: Theoretical Model and Monte Carlo Study

Abstract

Analytical model of nonradiative energy migration (homotransfer) within the set of chemically identical fluorophores distributed on the surface of a spherical nanoparticle is for the first time presented. The expression for emission anisotropy decay is obtained. The method of Green's function was used to solve the master equation describing this stochastic process. An expansion in powers of the fluorophore density to investigate this finite volume problem was employed. A very good result for the Green function directly related to emission anisotropy was obtained by using the Padé approximant. It was found that emission anisotropy decay depends strongly not only on the number of fluorophores linked to the spherical nanoparticles but also on the ratio of critical radius to nanoparticle radius, which is crucial for the optimal design of antenna-like nanostructures. Coherence of the model was verified by Monte Carlo simulations and excellent quantitative agreement was found between theoretical and Monte Carlo simulation results.