Modeling of light absorption and scattering by metal nanoparticles coated with organic dye J-aggregate

The results of the theoretical study of optical properties of composite nanoparticles consisting of a metal core (Ag, Au, Cu, Al, Ni, Cr) and a J-aggregate shell of organic dye are presented. Light extinction, absorption, and scattering coefficients in colloidal solutions were calculated within the model based on the Mie theory modified taking into account dimensional phenomena and complemented by calculations of complex dielectric functions of the metal core and J-aggregate shell. The model adequately explains the features observed in light absorption and scattering spectra by hybrid nanoparticles, associated with the plasmon resonance in the metal core and with electronic excitation of the J-aggregate. The strong dependence of the results on geometrical parameters of nanoparticles and dielectric constants of core and shell materials was demonstrated. Methods for controlling the effects of the plasmon-exciton interaction in the system and optical properties of composite materials developed based on nanoparticles under study are discussed.