12: X-ray Diffraction and Mineral Analysis
- Page ID
- 17521
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- 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: X-ray Diffraction
- 12.1.1: Intensity of Diffraction
- 12.1.2: Intensity of Diffraction- Halite
- 12.1.3: X-ray Patterns, Symmetry and Mineral Identification
- 12.1.4: Extinctions
- 12.1.5: Indexing Patterns and Determining Cell Parameters
- 12.1.6: Uncertainties
- 12.1.7: Single Crystal Diffraction
- 12.1.8: The Discovery of X-rays and Diffraction
- 12.1.9: What are X-rays?
- 12.1.10: Interactions of X-Rays and Atoms
- 12.1.11: Interference of X-Ray Waves
- 12.1.12: Diffraction by a Row of Atoms
- 12.1.13: Diffraction by Planes of Atoms
- 12.1.14: Routine X-Ray Analysis- Powder Diffraction
- 12.1.15: Data and Processing
- 12.1.16: Effects of Different X-ray Wavelengths
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)