X-ray crystal truncation rod scattering is a powerful method in surface science, based on analysis of surface X-ray diffraction patterns from a crystalline surface.
For an infinite crystal, the diffracted pattern is concentrated in Dirac delta function like Bragg peaks. Presence of crystalline surfaces results in additional structure along so-called truncation rods. Crystal Truncation Rod measurements allow detailed determination of atomic structure at the surface, especially useful in cases of oxidation, epitaxial growth, and adsorption studies on crystalline surfaces.