Electron Diffraction

Electrons can diffract off crystal lattices — Davisson and Germer's 1927 experiment was the first direct evidence of matter waves.

An electron beam incident on a single-crystal nickel target produces a diffraction pattern, analogous to X-ray diffraction.

Bragg's law applies: 2d·sin θ = nλ — the same as for X-rays — but here λ = h/p (de Broglie).

G.P. Thomson independently showed electron diffraction through THIN foils, getting Debye-Scherrer rings.

Confirmed de Broglie's hypothesis quantitatively: the measured λ matched h/p for the electron's KE.

Modern applications: electron microscopy (resolution depends on small λ), low-energy electron diffraction (LEED) for surface analysis.

Neutrons also diffract — used in neutron crystallography (better for light atoms like H than X-rays).