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When using an x-ray microbeam, rotation of the sample relative
to the microbeam is not allowed. There are two critical
problems associated with rotations and microbeams:
To avoid rotations, the
sample is scanned beneath the incident x-ray microbeam within
the focal plane. At each step in the scan, diffraction
data can be collected via a CCD detector.
Either white beam or
monochromatic beam can be used to perform a microdiffraction
scan. White beam is used when the grain size of the
material is greater than or about equal to the x-ray beam size.
With white beam, data is collected as Laue patterns from any
crystallites within the diffracting volume. Monochromatic
beam is used when the grain size is much less than beam size.
In this case, the sample can be viewed as a powder. Data
is collected in the form of diffraction rings.
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