Surface photoelectric effect induced by small clusters impinging on solid surfaces

The contribution of the surface photoelectric effect to the emission of lig ht is calculated within a free electron model assuming that small ionized A g-n(+) clusters (n = 1, ..., 5) bombard a silver surface. The model propose d describes the creation of metal holes in the conduction band as a consequ ence of the resonant capture to the unoccupied ground state of the ionized cluster. Next, another metal electron fills the hole left and the excess en ergy is emitted as a photon, while the surface accounts for the difference in momentum. The photon spectra and, in particular, the trend of the photon yield vs the cluster size are very sensitive both to the ionization potent ial and to the energy shirt of the cluster ground state. Photon spectra due to this process are compared to our previous calculations of photon spectr a originated by a radiative capture process directly to the cluster ground state. We find that emission of photons is mainly due to this later process . (C) 2000 Elsevier Science B.V. All rights reserved.