How do scientists use X-rays to study the structure of crystals?

1 Answer
Feb 29, 2016

They use X-rays to create Diffraction Patterns when passing through crystals and study these patterns.

Explanation:

A diffraction pattern is, basically, a photograph of a...slit illuminated by light!
Light passes through a narrow slit and get diffracted (it spreads out) creating waves that can interfere one with the other; you can "see" this interference as bright and dark dots or lines.

In the case of a crystal the slits (many of them!!!) are the separations in the lattice structure of the crystal; but these are very narrow so you'll need a small wavelength/high frequency kind of radiation to interact with these narrow slits....i.e., X-rays! Not only this; when emerging, after interferring, the pattern of dark and bright dots projected, for example, on a screen carries information (width, height, disposition...) of the slits that originated it!!!

The scientist then takes a picture of the resulting figure obtained (interference pattern) and from this he can "read" the internal structure of the crystal!

http://www.chemistryviews.org/details/ezine/2064331/100th_Anniversary_of_the_Discovery_of_X-ray_Diffraction.html and http://www.frontline.in/static/html/fl2823/stories/20111118282311400.htm
[Schematic (left) and diffraction pattern of an aluminium-manganese (Al-Mn) alloy (right)]