Plasmon coupling and aging effect in CsCl–Ag thin films

Abstract

Cesium chloride-silver thin films were prepared on glass substrate by thermal evaporation technique. Optical, structural and morphological properties of as deposited of various thicknesses and aged films were studied. Multiple plasmon bands have been observed in the UV-visible spectra of all the nano-composite films due to formation of near-spherical silver nano-particles. Position and intensity of the peak were found to be a function of particle size and inter-particle distance. The prominent plasmon peak of as deposited films showed a red shift, due to the increase in particle size, with increasing film thickness at the rate of 0.06 nm shift per 1 nm film thickness and peak at higher wavelength showed 0.75 nm red shift per 1 nm change in film thickness due to the decrease in inter-particle distance. Also, in aged sample the film revealed 18 nm blue shift with 216 h of aging due to an increase in inter-particle separation between silver nanoparticles. The manuscript investigates and reports the cause for the changes observed.