Random array, diffraction pattern

The intensities of the diffraction lines depend upon the factors already mentioned, but further corrections must be included if the calculated intensities are to correspond accurately with the observed intensities. An important factor is the multiplicity of the reflections in the powder pattern, p. This correction term can be easily understood by deriving the powder pattern from the diffraction spot pattern of a single crystal (Figure 6.18a). The intensity of each spot is well defined, and the intensity of say, the 200 spot, 7(200), can be measured independently of all other reflections. If an X-ray beam is incident upon a random array of crystals, instead of a single crystal, each diffraction spot will lie at a... 

Figure 7.6. The diffraction pattern produced by a set of round (spherical) profiles can provide information about the arrangement of the profiles in the array, a) A single round profile and its diffraction pattern, b) A regular array of profiles like that of (a) results in a diffraction pattern which looks like a regular grid of dots of light, c) A random group of profiles like that of (a) produces a diffraction pattern similar to that of the single profile.

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