The 1927 Davisson–Germer experiment showed that electrons display diffraction.
Clinton Davisson and Lester Germer directed electrons at a nickel crystal and measured the intensity of electrons scattered at different angles. At particular angles, the intensity rose sharply, forming a pattern explained by diffraction from the regularly spaced atomic planes in the crystal.
The observations agreed with Louis de Broglie’s proposal that moving particles have associated wavelengths. They therefore provided direct evidence for the wave nature of matter and helped establish wave–particle duality in quantum physics.
A common confusion is to call the result interference alone. The measured peaks arose from coherent scattering and are conventionally described as electron diffraction, analogous to X-ray diffraction. Davisson and Germer shared the 1937 Nobel Prize in Physics with George Paget Thomson for demonstrating electron diffraction.