Grazing incidence diffraction

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Grazing incidence diffraction geometry. The angle of incidence, a, is close to the critical angle for the sample. The beam is diffracted in the plane of the surface of the sample by the angle 2th, and often also out of the plane. Grazing incidence diffraction GIXD.png
Grazing incidence diffraction geometry. The angle of incidence, α, is close to the critical angle for the sample. The beam is diffracted in the plane of the surface of the sample by the angle 2θ, and often also out of the plane.

Grazing incidence diffraction (GID) is a technique for interrogating a material using small incidence angles for an incoming wave, often leading to the diffraction being surface sensitive. It occurs in many different areas:

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<span class="mw-page-title-main">Grazing-incidence small-angle scattering</span>

Grazing-incidence small-angle scattering (GISAS) is a scattering technique used to study nanostructured surfaces and thin films. The scattered probe is either photons or neutrons. GISAS combines the accessible length scales of small-angle scattering and the surface sensitivity of grazing incidence diffraction (GID).

The angle of incidence, in geometric optics, is the angle between a ray incident on a surface and the line perpendicular to the surface at the point of incidence, called the normal. The ray can be formed by any waves, such as optical, acoustic, microwave, and X-ray. In the figure below, the line representing a ray makes an angle θ with the normal. The angle of incidence at which light is first totally internally reflected is known as the critical angle. The angle of reflection and angle of refraction are other angles related to beams.

References

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