Diagnostic of Surface Plasmons Resonances in Nanosized Gold Films by Modulation Polarization Spectroscopy

Abstract

Isotropic reflection angle θρ=0 of s- and p-polarized radiation is a special parameter of the modulation polarization spectroscopy technique in study of nanosized gold films with mass thickness of d = 4.5–50 nm (Kretschmann geometry). Systematization of resonant mechanisms of surface plasmons’ excitations was performed using spectral characteristics of the angle of isotropic reflection θρ=0(λ), which had not been reviewed earlier in detail. Resonant wavelengths of plasmon oscillations for continuous films d = 15–50 nm and excitations of localized surface plasmons on isolated non-interacting Au nanoparticles and between Au nanoparticles caused by dipole fields’ interactions for island films of d = 4.5–10 nm were obtained. The experimental data were confirmed by theoretical calculations. Effective optical parameters of continuous and island Au films were obtained. Radiative and non-radiative modes of surface plasmons’ oscillations have been analyzed at various incident angles. The correlation between film thickness and plasma oscillations was demonstrated.