Optical properties of bimetallic nanospheres: effect of diffuse electron density profiles at the boundary surfaces.

The effect of diffuse electron density at the boundary surfaces of Au-core Ag-shell bimetallic nanospheres on their optical properties such as extinction spectra is investigated by considering a multiple shell model for both the interfaces consisting of exponentially decreasing electron density profiles corresponding to a minimized energy density functional. The dielectric constants for the shells of varying electron density have been obtained by proposing a new simple approach. The diffuseness of the electron density at the boundary surfaces is found to give rise to peak broadening to some extent and also seems to favor the experimental spectra.