Synthesis, linear extinction, and preliminary resonant hyper-Rayleigh scattering studies of gold-core/silver-shell nanoparticles: comparisons of theory and experiment

Gold-core/silver-shell nanoparticles featuring core diameters of 13 or 25 nm were prepared in aqueous solution. Silver-coated gold nanoparticles have two distinct plasmon absorption bands whose relative intensities depend on the shell thickness – features that are captured well by classical Mie theory. The core/shell spectra are not simply linear combinations of the pure-component spectra. Theory shows that shell dielectric effects upon the core can cause broadening, shifting, and, in some cases, damping of dominant extinction spectral features. Preliminary studies show that core–shell particles are reasonably efficient hyper-Rayleigh scatterers under conditions of two-photon resonance or near resonance with a high-energy plasmon band.