Top: crystal truncation rod scan of a crystalline bismuth film epitaxically grown on Si 111 taken at 18 keV. The oscillations show the film thickness. Bottom: reflectivity of a free water surface at 296 K obtained using LISA at 25 keV. The data (symbols) were recorded in ∼1 h. The dashed lines show a zero-roughness calculation. The solid line includes the surface roughness which is induced by capillary waves.