ELECTROMAGNETIC-INTERACTIONS WITH ROUGH METAL-SURFACES

When surfaces are structured on the scale of the wavelength, we can ex pect incident light to be strongly modified by the surface. This is es pecially the case when the surface is metallic. We have developed a fo rmalism for computing these modifications, closely analogous to electr on scattering theory, which we briefly review and present some results for optical properties of, and electron energy loss in, colloids. Our main theme is another effect associate with rough or structured metal lic surfaces: Surface Enhanced Raman Scattering, or SERS. We model the rough surface by a periodic array of spheres and obtain the correct m agnitude for the enhancement and for the frequency shifts observed.