Theoretical study of the optical absorption properties of Au–Ag bimetallic nanospheres

The dependence of nonlinear optical response properties of bimetallic alloying and core–shell structure spherical nanoparticles was investigated as a function of relative composition. Numerical calculations based on Drude model and quasi-static theory were developed to describe these absorption properties. With the increasing gold content, the absorption peaks of both alloying Au–Ag nanospheres and core–shell structure nanospheres red-shift from 402 to 526 nm in a nonlinear way. Furthermore, the linearity of alloying nanospheres is better than that of core–shell structure model. In core–shell structure nanospheres, the shell composition characters play a more important role to influence the optical properties of the bimetallic nanoparticles.