Theory of second-harmonic generation by metal overlayers

Abstract

Changes in the intensity of second-harmonic (SH) radiation caused by adsorption of metal overlayers on a metal substrate are calculated using the jellium model. A density-functional treatment of the electronic response leads to a longitudinal SH response versus coverage curve with a maximum at a coverage below that of a single full adsorbed layer. We find that this maximum occurs at the same coverage at which the work function exhibits a minimum. Qualitatively similar structure is seen in recent measurements of the SH intensity as a function of overlayer coverage.