Optical properties of a metal sphere with a diffuse surface

The effects of microscopic diffuseness of the boundary surface of metal spheres on the surface plasmons and the optical properties are investigated. It is found that the surface-plasmon frequencies are lower than those of a sphere with a sharp surface. The extinction cross sections of small spheres with diffuse surfaces are calculated, and a corresponding shift of the absorption maxima towards the low-frequency side is found to occur, as well as a broadening of the peaks. The relationship of these calculations to previous optical measurements performed on small metal spheres is discussed.