Davisson-Germer Experiment (1925)
Low-energy electrons scatter from the surface of a crystal.
Electrons were diffracted like waves with l= h/mv
As electron energy decreased, the diffraction pattern spread out, and vice-versa.
Notes:
Electrons were also a fairly recent discovery in the early days of Quantum Mechanics. It was well established hat electrons have particle properties like well-defined mass and electric charge. When Davisson and Germer directed a stream of low-energy electrons at a crystalline surface, the individual electrons could be detected scattering off at different angles. However, after a large number of electrons had been observed, it was clear that as a whole they formed a diffraction pattern very much like x-rays scattering from a crystal .