 Batterman in the 1960s, the availability of synchrotron light has stimulated the application of this interferometric technique to a wide range of problems in surface science.An X-ray standing wave (XSW) field is created by interference between an X-ray beam impinging on a sample and a reflected beam.The reflection may be generated at the Bragg condition for a crystal lattice or an engineered multilayer superlattice; in these cases, the period of the XSW equals the periodicity of the reflecting planes.