МЕТОД ОЦІНЮВАННЯ СТУПЕНЯ ЕЛЕКТРОМАГНІТНОЇ ВЗАЄМОДІЇ ДВОХ МЕТАЛЕВИХ НАНОЧАСТОК У ОПТИЧНОМУ ДІАПАЗОНІ ХВИЛЬ

A method for calculation the scattering characteristics of a model consisted of several silver nanoparticles, which have a finite dielectric permittivity in the optical band (wavelength from 300 nm to 900 nm) is proposed. Developed numerical method is based on the Müller surface integral equation (IE) set solution for a group of nanoparticles. The values of a total scattering cross-section (TSCS), extinction cross-section (ECS) and absorption cross-section (ACS) were obtained for a model of two nanoparticles of ellipsoidal shape and different sizes (from tens to hundreds of nanometers). Mentioned cross-sections were calculated for various distances between nanoparticles  and sounding directions, on two orthogonal polarizations. The calculations were carried out taking into account the electromagnetic (EM) interaction between nanoparticles when determining the densities of equivalent electric and magnetic surface currents, and also without accounting for the specified interaction. The relative errors of calculating the values of TSCS and ACS in the case of neglecting the EM interaction between nanoparticles were obtained. EM evaluation of the interaction between nanoparticles of two different geometric sizes at variable distances between them at a fixed wavelength of 300 nm of the visible optical spectrum was carried out. The minimum distances between nanoparticles, at which their EM interaction can be neglected while maintaining the specified accuracy of calculations, have been determined. The obtained data make it possible to significantly reduce the dimensions of the Müller IE set, the amount of required computer memory, and the calculation time when studying the scattering characteristics of a large number of nanoparticles. The proposed method can be generalized to nanoparticles of noble metals. Since the electrical dimensions of nanoparticles also change when the irradiation wavelength changes, the direction of further research is to study the intensity of EM interaction at other wavelengths, in particular resonant ones, as well as for the entire visible spectrum from 300 nm to 900 nm.