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Calculated Intensity


Crystals are regular, ordered structure, and contain billions upon billions of atoms arranged in regularly-spaced lattice planes. These lattice planes act as diffraction gratings for radiation whose wavelength is similar to the lattice plane spacing (e.g., x-rays and neutrons can be diffracted by crystals).

The intensity of diffraction from a particular set of lattice planes depends on the type and arrangement of atoms parallel to the lattice planes. Atoms lying between the lattice planes are "out of phase" and reduce the intensity of the scattering.

Knowing the orientation of a lattice plane (which is determined by its Miller Indices), and details of the crystal structure (its lattice parameters, symmetry, and asymmetric unit), CrystalDiffract can calculate the intensity for any reflexion.


Note: The absolute intensity of an x-ray or neutron reflexion is related to the square of the amplitude scattered by one unit cell in the crystal. Because different materials have different-sized unit cells, it is necessary to normalize the resulting intensities. CrystalDiffract scales the intensities so that they correspond to the amount scattered by one cubic centimetre (1cm^3) of solid material. You can therefore directly compare the x-ray or neutron intensities of different materials, plotted in different windows: they have the same absolute intensity scale.


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