Влияние поглощения матрицы на ближнеполевые и спектральные характеристики рассеяния плазмонных сферических наночастиц

Abstract

Regularities of a size dependence of extinction and absorption efficiency factors as well as of near-zone and far-zone scattering efficiency factors are studied in the spectral range of the surface plasmon resonance of absorption (SPRA) for silver spherical nanoparticles placed into absorbing matrixes with complex refraction index nm+ikappam. Numerical simulation was made with the use of the Mie theory for absorbing matrixes. Approximation of the electron mean free path limitation was used in order to take into account the intrinsic size effects into a metal nanoparticle which consist in a size dependence of its dielectric characteristics. We shown that a growth of matrix absorbency leads to a strong suppression of resonances of extinction (Qext) and near-zone scattering (QNF) efficiency factors without any essential changing of their spectral position. We established that for any fixed wavelength in the spectral range of the SPRA the values of Qext and QNF depend on metal nanoparticle sizes nonmonotonically at kappam = 0–0.1. The RNP optimal value, which corresponds to the maximal values of efficiency factors for the given material of plasmonic nanoparticles, increases at the matrix absorbency growth. The intrinsic size effects contribution to the efficiency factors resonance suppression decreases at the enhancement of nanoparticle sizes and/or matrix absorption. As an example of a real absorbing matrix with a dispersion of relraction index we considered the nickel phtalocyanine matrix (NiPc), which is interesting from the point of view of photovoltaic applications.