In 1927, Clinton J. Davisson and Lester H. Germer directed a beam of electrons of precisely known energy at the surface of a single crystal of nickel.

The intensity of the scattered electrons was measured at different angles and showed peaks exactly where the wave theory predicted.

The electrons mostly scatter from atoms near the surface of a material, so this technique, called Low Energy Electron Diffraction (LEED for short), is often used to determine how atoms are arranged on surfaces.

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