Microgeometry and effective permittivity of discontinuous metal films

This work deals with the investigation of dielectric and optical properties of discontinuous metal films over a wide range of filling factors each side of the percolation threshold. A phenomenological two-parameter representation is used for the effective permittivity (epsilon) over tilde of such systems. In order to test the proposed approach, we have taken for gold films on a glass substrate the transmittance spectra in the visible and near-IR regions. It is shown that the representation used for the effective permittivity enables us to adequately describe the experimental transmittance spectra. The parameters entering the above representation are determined and the relationship between them and film microgeometry is discussed.