Optical absorption of submonolayer silver films: Size effect of ϵ free and ϵ bound in small island particles

Abstract

Optical absorption spectra of submonolayer silver films deposited on a fused quartz ATR prism were measured. Optical plasma resonance absorption peaks both for p- and s-polarized light were observed at near 3.5 eV. The observed spectra were interpreted well by the model of two-dimensionally distributed ellipsoids of rotation applying the Drude formula and the classical size effect to the free electron part of the dielectric constants of silver island particles ϵ free and the bulk value shifted to the higher energy region to the bound electron part ϵ bound. It was found that the amount of the shift increases with decrease of mean thickness of silver.