The reflection coefficients for perpendicular and parallel polarization of a germanium-mercury interface have been measured as a function of angle of incidence at a wavelength of three microns. There is in general good agreement with theory although at the principal angle, the parallel component of polarization is absorbed more strongly than indicated by theory.
N. J. HARRICK, "Reflection of Infrared Radiation from a Germanium-Mercury Interface," J. Opt. Soc. Am. 49, 376-378 (1959)