Diffraction - to analyse the structure and properties of materials at the atomic level
Diffraction forms the corner stone of material characterisation, occuring when an X-ray beam interacts with a ordered material. The scattered X-rays undergo constructive and destructive interference as a result of their interaction with the material. The angular directions of possible diffraction peaks depend on the arrangement of the atoms within the unit cell. The intensities of the signals depend on the type and arrangement of atoms in the crystal structure. Each material gives different and characteristic diffraction patterns, essentially a molecular fingerprint.
The technique is therefore a very powerful tool to identify and characterise compounds based on their diffraction pattern. Diffraction can be employed to investigate ordered materials, for example crystals of both small molecules and large molecules like proteins, and powders.
It can also be used to monitor structural changes in materials undergoing a process such as gas absorption or laser heating. It can be used to measure strains in materials under load, by monitoring changes in the spacing of atomic planes.