Resonance light scattering characters of core-shell structure of Au-Ag nanoparticles

Nanoparticles containing gold cores and silver shells have been synthesized via electrochemical method. The resonance light scattering spectrum has been studied at room temperature. Scattering features show two peaks at 370 nm and 570 nm, which result from the scattering of solid silver nanoparticles and silver coated gold nanoparticles, respectively. The calculation results based on quasi-static theory indicate that with the increasing ratio of the core radius to the total radius of the compound nanoparticles, the peak of scattering cross section decreases first then increases and reaches the minimum when the ratio is about 0.5. And meanwhile the scattering peak red shifts nonlinearly. Furthermore, with the increasing dielectric constant of surrounding medium, the scattering peak increases monotonic and red shifts.