Davisson–Germer experiment

A 1927 experiment in which electrons scattered from a nickel crystal produced diffraction peaks, confirming the wave nature of electrons.

Electron diffraction: The scattering of electrons by matter that produces interference patterns characteristic of waves. The experiment’s diffraction peaks are a direct instance of this broader phenomenon.
Clinton Davisson: American physicist whose experiments on electron scattering from metals helped establish electron diffraction. He led the laboratory work that produced the nickel-crystal diffraction results.
Wave–particle duality: The principle that quantum objects exhibit both wave-like and particle-like properties. Electron diffraction made the wave aspect of a particle observable in the laboratory.
Compton effect: The wavelength shift of X-rays scattered by electrons, demonstrating radiation’s particle-like momentum transfer. It demonstrated particle-like behavior of waves, complementing the experiment’s wave-like electrons.
Bragg's law: A relation connecting X-ray wavelength, crystal-plane spacing, and diffraction angle. Its condition predicts the angles at which waves scattered by nickel planes reinforce.
Lester Germer: American physicist who collaborated with Clinton Davisson on electron-scattering experiments. He helped obtain and interpret the diffraction measurements after the laboratory’s nickel target was annealed.
Electron microscope: A microscope that uses electron beams to form images at resolutions beyond those of visible-light microscopes. Electron wave behavior underlies the microscope’s resolution and image formation.
Thomson scattering: The classical elastic scattering of electromagnetic radiation by free charged particles. It describes a non-quantum scattering model, unlike the electron diffraction pattern observed here.
de Broglie wavelength: The wavelength associated with a particle, equal to Planck’s constant divided by its momentum. The measured peak angles matched wavelengths calculated for the accelerated electrons.
Louis de Broglie: French physicist who proposed that matter has wave properties associated with its momentum. His 1924 hypothesis supplied the electron wavelength tested by the experiment.

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