Nonlocal effects in ellipsometry of metallic films on metals

A simple but exact generalization of optical surface response formalism beyond the long wavelength approximation (LWA) is developed and evaluated within the hydrodynamic approximation for a nonlocal three layer model describing a metal film between a dielectric and a metallic substrate. In the LWA an explicit analytical formula for the ellipsometry ratio ρ = r_p/r_s in terms of bulk optical constants of the layer materials is given. Model calculations show that classical optics can reproduce nonlocal results only with a strange effective dielectric function of the film reflecting substrate properties up to large film thickness.