RAMAN-SCATTERING BY BULK PHONONS IN MICROCRYSTALLINE SILVER AND COPPER VIA ELECTRONIC SURFACE EXCITATIONS

In Raman scattering from cryocondensed metal films one observes the bu lk acoustic phonons. This is not caused by the laser field which penet rates the metal, but via the scattering of optically excited intrasurf ace band electron hole pairs by the phonons. Phonons with wave vector Q contribute to the Raman signal according to the scattering probabili ty Steal of the image states by surface roughness, where ri is the pro jection of Q onto the low index facets having occupied electronic surf ace states, in the present case mainly of (111) orientation.