https://doi.org/10.1351/goldbook.09214
Measurement method for surface and interface roughness and density, layer thickness of thin layers, and electron density profile achieved by reflecting X-rays from a flat sample and analysing the reflected intensity as a function of angle.
Note: Monochromatic X-rays of low divergence are required. Many layers can be modelled, with thicknesses between about \(\pu{1 nm}\) and a few \(\pu{\upmu\!m}\), and (subject to conditions) fitted to the data. The surface needs to be flat over the beam footprint of typically \(\pu{10 mm}\) to \(\pu{40 mm}\).
See also: specular X-ray reflectometry