Method of frustrated total reflection in spectroscopy of surface polaritons in almost perfectly conducting metals

The standard technique for surface polaritons excitation by a prism coupling in Otto configuration is applied for investigation of almost perfectly conducting (pec) metals like tantalum irradiated by a collimated He-Ne laser radiation (λ ₀ = 632.8 nm). In pec metals the imaginary part of the relative dielectric permittivity (ɛ″) is quite larger than the modulus of the real part of the same quantity (ɛ′ < 0, ɛ″ ≫ | ɛ′ |). Under this condition the single Lorentz dip of the reflectivity coefficient is proven to exist and is given in an analytical form, which follows from simplification of the usual multilayer Fresnel formula. In the case of a deterministically curved metal surface an approximate solution to the reduced Rayleigh integral equation appropriate for the Otto configuration is also given. These two theoretical deductions are compared with experimental data that have been produced by us for the reflectivity into the prism region from a bulk tantalum sample.