Modulation polarimetry of the topological effect in gold-organic nanocomposite films

Abstract

The phenomenon of surface plasmon resonance in composite films consisting of gold nanoclusters in matrices of organic molecular materials calix[4]arene and poly(N-vinylcarbazole) has been investigated. The internal reflection coefficients Rs2 and Rp2 of s- and p-polarized light and their physical difference ρ = Rs2 − Rp2 have been measured according to the Kretschmann scheme as a function of the angle of light incidence θ at different wavelengths λ in the range 400–1000 nm. The angular characteristics reflect the cluster structure of the films, which is confirmed by electron microscopy. A topological size effect has been revealed. This effect is associated with the dependence of the excitation energy efficiency of surface plasmons on the azimuth of the linearly polarized light, the shape, and the distribution of nanoclusters in the coordinate space. The dependences ρ(λ) demonstrate that the local plasmon resonance is excited by both s- and p-polarized light, whereas the polariton resonance is excited by s-polarized light. The sign of the curvature of the dependence ρ(θ) determines the predominance of the excitation energy efficiency of electromagnetic modes with one of the two states of polarization of the excitation radiation.