Theoretical study of the optical absorption behavior of Au/Ag core–shell nanoparticles

The dependence of linear optical response properties of bimetallic core–shell spherical nanoparticles is investigated as a function of size and relative composition. Two kinds of schematic models have been tested for describing the dielectric behavior of bimetallic particles and the related linear electromagnetic response: (i) Drude model, in conjunction with bulk dielectric data relative to the pure metals, in the assumption of a simple combination law; (ii) DFT-based approach to the dynamic polarizability of a binary particle, with the nature of the metals involved taken into account through their Wigner–Seitz radius.