Theory of light scattering from a random metal surface: Excitation of surface plasmons in a Ag film

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Abstract
The scattering of light by a silver film with a random rough surface and the excitation of surface plasmon modes at the metal surface are theoretically studied in detail by means of the new stochastic treatment. The silver film is assumed sandwiched between the air and a crystal and a plane wave is incident through the crystal to excite the surface-plasmon mode. The stochastic formulation is developed for the stated problem and approximate solutions are obtained for the coherent and incoherent scattered waves involving the optical theorem. Details of the scattering characteristics are numerically calculated for various combinations of film thickness, surface roughness, and correlation length. The angular pattern of incoherent scattering into the crystal is shown to have two sharp resonant peaks due to the excitation of the surface plasmon, which are directly observable by an experiment.