Low energy investigations of photoemission from indirect optical excitations

Low energy photoemission from indirect excitations has been studied for a variety of crystallographic orientations on the curved surface of single crystal cylinders of copper and gold. Both at normal and oblique incidence of the light, we have observed pronounced crystallographic and polarization anisotropies of the photoelectron current. The results are shown to disagree with existing theoretical models of indirect transition mechanisms. The photoemission-into-electrolyte technique has been used to obtain a sufficiently low threshold for electron emission.