beam footprint

in X-ray reflectrometry
https://doi.org/10.1351/goldbook.09436

Area on the specimen irradiated by X-rays in X-ray reflectrometry.

Notes:
  1. In typical commercial equipment, the beam width is 200 μm, so at 0.3 ∘ incident angle, the beam footprint is 38 mm long; at 1 ∘, it is 11.5 mm and at zero incidence angle it is infinite. For 100 μm incident beam width, these values are halved.
  2. The beam footprint along the beam direction can be reduced by the use of a suitable knife-edge diaphragm mounted in a plane that is normal to the sample surface and whose normal, in turn, aligns with the beam azimuth. The knife-edge is parallel to, and adjusted to be close to, the surface at the point where the X-ray beam centre strikes the sample surface. This closeness limits the footprint size but also reduces the measured signal intensity.
Source:
PAC, 2020, 92, 1781. (Glossary of methods and terms used in surface chemical analysis (IUPAC Recommendations 2020)) on page 1847 [Terms] [Paper]
Citation: 'beam footprint' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.09436 RIS BibTex EndNote
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