Plasma resonance in granular silver films deposited on rough surfaces of NaCl and KCl single crystals

Granular silver films deposited on rough NaCl and KCl single-crystal surfaces exhibit, besides the low-frequency plasma-resonance band induced by the light-wave field and the field generated by the grain dipoles, a second, high-frequency plasma-resonance band, which is excited only by the light-wave field at the frequency ω₀ of the natural electron vibrations in the grains. The dielectric constant due to interband transitions was calculated from the known plasma frequency and the dielectric constant of the medium surrounding thegrains, the plasma frequency ω_p of the granular films, and the measured frequency of the maximum of surface plasmon vibrations in solid films. The results obtained agree with the data quoted by other authors.