An anomalous change in the frequency of plasmon resonances of island metal films upon their contact with some polar organic media

Abstract

We have examined the changes in the extinction of island metal films that occur as a result of their contact with a liquid crystal or polymethylmethacrylate. The morphology of surface nanostructures has been investigated. We have revealed that, upon immersion of an island metal film into a liquid medium molecules of which are polar, the shift of the plasmon resonance in the extinction spectrum and the increase in the extinction at the frequency of this resonance can substantially differ from the shift and the extinction increase theoretically calculated for an isotropic surrounding substance. We have shown that the reason for these differences is the local anisotropy of the refractive index of the medium in the immediate vicinity of metal particles, which is determined both by the shape of particles and by the degree of occupation of the substrate surface.