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12: X-ray Diffraction and Mineral Analysis

  • Page ID
    17521
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    Key Concepts
    • X-radiation, discovered in 1895, was the key to understanding atomic arrangements in crystals.
    • X-rays may have many different wavelengths but for diffraction studies we isolate one.
    • When X-rays interact with atoms, the rays are scattered in all directions; coherent scattering by multiple atoms produces X-ray diffraction.
    • Directions of diffraction tell us the spacings between planes of atoms in a crystal; intensities of diffraction tell us the number of atoms on those planes.
    • We use a powdered sample for routine mineral identification.
    • Compositional variations cause slight variations in X-ray patterns.
    • Single crystal diffraction data allow crystallographers to figure out where atoms are in a unit cell.
    • Scanning electron microscopes allow high-magnification imaging of mineral crystals and of thin sections.
    • Electron microprobe data yield mineral compositions based on X-ray intensities.
    • Other important analytical techniques include X-ray fluorescence, atomic absorption, inductively coupled plasma mass spectrometry, ion microprobe, Mössbauer spectroscopy, visible and infrared spectroscopy, and Raman spectroscopy.
    12.1.jpg
    Figure 12.1: A powder X-ray diffractometer

    Thumbnail: An X-ray diffraction pattern of a crystallized enzyme. The pattern of spots (reflections) and the relative strength of each spot (intensities) can be used to determine the structure of the enzyme. CC BY-SA 3.0; Jeff Dahl via Wikipedia)


    This page titled 12: X-ray Diffraction and Mineral Analysis is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by Dexter Perkins via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.

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