Plasma resonance of silver nanoparticles deposited on the surface of submicron silica spheres

Silver nanoparticles of 20 and 70 nm, respectively, were deposited on the surfaces of submicron silica spheres. Plasma resonances of the submicron silica spheres with dense and uniform silver layer were investigated using UV/vis absorption spectra. It was found that the silver plasma resonance band of the silica–silver core-shell spheres was broadened and shifted to longer wavelength several hundreds nanometers. The dipole–dipole interactions of neighboring silver particles and Mie scattering of silver shell as a whole may serve as the mechanism of such shift and broadening.