Optical properties of aggregated Ag and Au thin films—MG approach

Abstract

The effect of aggregation on the optical properties of Ag and Au metals in thin‐film form is analyzed with the simple Maxwell‐Garnett theory. Free‐electron damping and interband transitions in the particles are considered, along with the effect of an interparticle dielectric material. Numerical analysis shows that interband transitions severely damp the free‐electron conduction resonance and that they introduce bound‐electron resonance structure in the dielectric functions of the aggregated medium. These results are used to interpret experimental data.