X-rays {x-ray crystallography}| {x-ray diffraction} can find atom positions and electron densities. X-rays have wavelength 0.1 nanometers, the same as atom spacing in crystals. Crystal planes reflect x-rays. Large ions polarize easily. Small ions have large field. Cations are less polarizable than anions, because positive charge holds electrons better. Transition metals have bigger fields.
process
Powder rotates for instrument to check all interplanar distances and make one line for each plane, on film. Alternatively, one crystal rotates for instrument to make differing intensity-point patterns, on film.
Interference pattern can calculate spacing between crystal planes: path-length difference = 2 * d * sin(A) {Bragg condition}, where d is distance between planes, and A is angle.
5-Chemistry-Analytical Chemistry
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Date Modified: 2022.0225