The role of bound electrons in the non-local surface response of metals

P-polarized light has the unique feature of probing the surface region of a metal which gives rise to effects not taken into account in a classical (Fresnel) treatment. Previous calculations of this non-local effect have been restricted to free-electron metals. Within a simple framework we will here consider the modifications because of the presence of bound electrons. The somewhat surprising result is that a system with both free and bound electrons will still be possible to analyze in free-electron terms, provided we plot the experimental results with a normalization which removes all dependence of the angle of incidence.