Fresnel plot

X-ray and neutron reflectivity curves are often displayed as Fresnel plots, which means plotting $\scriptstyle R(q_{z})\times q_{z}^{4}$ vs. $\scriptstyle q_{z}$ (instead of simply $\scriptstyle R(q_{z})$ vs. $\scriptstyle q_{z}$). This representation divides-out the generic functional form of the Fresnel reflectivity from a single idealized interface (which goes as $\scriptstyle R_{F}\sim q_{z}^{-4}$). This is useful for highlighting the features/oscillations of the reflectivity curve, by suppressing the expected decay of the curve with angle.