(A) XR measurements of Aβm, FO, or NFO adsorbed to an air/water interface. Normalized by Fresnel reflectivity, XR data is plotted as a function of the scattering vector (qz), shown as points with experimental error. The fitted model is overlaid as a solid black line. (B) The electron density profile fitted results, normalized to water (ρ/ρwater), for Aβm, FO, and NFO adsorbed to the air/water interface are plotted as a function of depth into the liquid subphase (zero is the air/water interface). Slab model fits with and without interslab roughnesses are shown with black and colored lines, respectively. Data and results are offset for clarity. Measurements were collected one time.