Electromagnetic interaction of atoms with an evanescent light field in attenuated total reflection spectroscopy

Abstract

The electromagnetic interaction of atoms with an evanescent light field is investigated with photon energy density and photon energy flux density using the Fresnel–Maxwell equations. The theory provides expressions of absorption signal intensities in attenuated total reflection spectroscopy for the p- and s-polarizations of the incident light, and relates them to the Goos–Hänchen shift. For an electric dipole interaction, the energy stored in the electric field of an evanescent light governs the absorption process, and hence the photon energy density and the photon energy flux density should be estimated from the energy stored in the electric field. The violation of equality between the portions of the energy stored respectively in the electric and magnetic fields yields the difference of the absorption signal intensity and its dependence on the incident angle between the s- and p-polarizations.