Grazing incidence diffraction

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Grazing incidence X-ray and neutron diffraction, typically from a crystalline structure (abbreviation GIXD or GID), uses small incident angles for the incoming X-ray or neutron beam, so that diffraction can be made surface sensitive. It is used to study surfaces and layers because wave penetration is limited. Distances are in the order of nanometres. Below (typically 80%) of the critical angle of the surface material studied an evanescent wave is established for a short distance and is exponentially damped. Therefore Bragg reflections are only coming from the surface structure.

An advantage of GIXD is that the electric field at the critical angle is amplified locally by a factor of four, therefore the GIXD signal is stronger.