In order to interpret reflectance infrared spectra for the three-layer system vacuum-poly(perfluoropropyleneoxide)-gold, it was necessary to carry out a classical dispersion analysis for the complex refractive index, n2, of poly(perfluoropropyleneoxide). Also, experimental data for the refractive index of gold, n3, in the infrared was fit to a polynomial to render the real and imaginary parts suitable for computer modeling. The refractive indexes were then used to compute the changes in the infrared reflectance spectra, via Maxwell's equations, as a function of film thickness and angle of incidence.
J. Pacansky, C. D. England, and R. Waltman, "Infrared Spectroscopic Studies of Poly(perfluoropropyleneoxide) on Gold Substrates: A Classical Dispersion Analysis for the Refractive Index," Appl. Spectrosc. 40, 8-16 (1986)