Influence of Adsorbed Metal Atoms on Light Absorption by a Fused Silica Surface

Optical properties of submonolayer metal (silver, gold, and indium) films obtained by laser ablation on a fused silica surface have been investigated. Extinction and absorption spectra of silica and substrates with deposited films and difference spectra are obtained. The minimum values of the effective metal-film thicknesses, at which islands begin to nucleate and localized plasmon resonances manifest themselves, are determined. It is shown that the absorption of the silica substrate–metal film complex exceeds the sum of absorptions by the silica surface and metal atoms. A relationship between this phenomenon and charge transfer from metal to defects on the substrate surface is revealed.