First Measurement of the Discontinuity Jump in a Reflectivity Curve near Total Reflection Edge

A discontinuity jump occurs in a reflectivity curve at the total reflection edge when the reflecting surface is characterized by a long-range attractive potential V(z). We give a simple derivation of the result. Using a system of high molecular weight polymer chains in good solvent adsorbed at the free surface, we observe for the first time the predicted effect.