Scattering: X-Ray Standing Wave Techniques

Introduction The X-ray standing wave (XSW) technique provides an element-specific structural probe by using x-ray reflectivity to generate a " two-beam " interference field that in turn induces a spatial dependence to the x-ray spectroscopic yields from atoms within the field. The XSW technique is primarily used for resolving the atomic-scale structure at surfaces, interfaces, and thin films with applications spanning a wide scientific range including: materials science, solid-state and soft-condensed-matter physics, environmental-chemistry, geochemistry, biochemistry, and electrochemistry. As a fundamental wave phenomenon, the superposition of two coherently coupled X-ray plane-waves localizes the X-ray intensity into interference fringes of an X-ray standing wave (XSW) field (Figure 1). This effect, which is produced by an x-ray reflection, makes it possible to attain a periodic structural probe with a length-scale equivalent to the XSW period: