An X-ray diffractometer measures scattering intensity as a function of sample orientation, scattering angle or photon energy. Its essential elements are an incident X-ray beam, a mounted sample, controlled angular geometry and a detector recording the outgoing beam or pattern.
A monochromatic angle scan changes which reciprocal-lattice vectors satisfy the elastic diffraction condition. A position-sensitive detector can instead record many outgoing directions at once, while sample rotation brings further reflections into view. Converting the counts into structural information requires the wavelength, angular calibration, sample alignment and intensity corrections. A single crystal and a powder produce different sampling patterns. The recorded intensities contain both peak-position information about the lattice and structure-factor information about the atomic basis.
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