  The interaction of charges in dielectric materials is screened by the
dielectric constant of the bulk dielectric. In dielectric theories, screening
is assigned to the surface charge appearing from preferential orientations of
dipoles along the local field in the interface. For liquid dielectrics, such
interfacial orientations are affected by the interfacial structure
characterized by a separate interfacial dielectric susceptibility. We argue
that dielectric properties of polar liquids should be characterized by two
distinct susceptibilities responsible for local response (solvation) and
long-range response (dielectric screening). We develop a microscopic model of
screening showing that the standard bulk dielectric constant is responsible for
screening at large distances. The potential of mean force between ions in polar
liquids becomes oscillatory at short distances. Oscillations arise from the
coupling of the collective longitudinal excitations of the dipoles in the bulk
with the interfacial structure of the liquid around the solutes.
