The diffractometry of neutrons is a technique of analysis based on the Diffraction of the Neutron S on the matter. It is complementary to the Diffractométrie of x-rays. The measuring device used is called a Diffractomètre. The collected data form the diagram of diffraction or diffractogram . Diffraction taking place only on the matter Crystal line, one also speaks about X-ray crystallography . For the materials not-crystalline lenses, one speaks about diffusion.
The neutrons being of electric Charge neutral, they do not interact with the electronic clouds of the atoms of the crystal, whereas it is the case of x-rays. On the other hand, they interact with the atomic nuclei and the dipole moments. This difference between these two techniques in diffraction is translated in several ways:
- the neutrons are sensitive to the various isotopes of the same atom, which can sometimes pose problems of correction of absorption during the data processing (in particular for compounds containing of the Bore) and impose the use (often expensive) of only one type of isotope at the time of the crystalline growth of studied material;
- the neutron diffraction makes it possible to distinguish the light atoms, like the Hydrogène, which are invisible for x-rays because of their low numbers of electron S;
- for the same material, the differences in measurement on the interatomic distances from connection are in general tiny if one compares the neutrons results and x-rays, except in the case of the compounds containing of the hydrogen bonds;
- the neutrons are also sensitive to the magnetic moments in the crystal: it is possible to determine the magnetic structure of a material by neutron diffraction. In theory, that is also possible in the case of the diffraction of x-rays, but the interactions between magnetic x-rays and moments are so weak that times of measurement become very long and require the use of the Synchrotron radiation.
- detailed Description of the methods of analysis by neutron diffraction
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