X-ray Diffraction
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Background
X-ray diffraction (XRD) is a tool for characterizing arrangement of atoms in crystals and distances between crystal faces. This can be used to identify atoms and the crystalline form.
Significance
A thin film or layer of powder is fixed in the path of x-rays of a single wavelength. Opposite a sensor measures diffraction from the sample at a series of angles. The powder consists of tiny crystals randomly oriented. At certain angles on the sensor populations of crystals will be found at the correct angle so that Braggs Law is obeyed, resulting in a spike in X-rays. The output graph is x-ray intensity over 2 theta, the angle of the detector. [[Image:|thumb|300px|Bragg diffraction.png | Reflection (constructive interference) happens only where the wave path-length difference 2d sin θ equals an integer multiple of the wavelength λ. ]]