In physics, electron emission is the ejection of an electron from the surface of matter,^[1] or, in beta decay (β− decay), where a beta particle (a fast energetic electron or positron) is emitted from an atomic nucleus transforming the original nuclide to an isobar.

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• In Beta decay (β− decay), radioactive decay results in a beta particle (fast energetic electron or positron in β+ decay) being emitted from the nucleus

• Thermionic emission, the liberation of electrons from an electrode by virtue of its temperature
  • Schottky emission, due to the:
    • Schottky effect or field enhanced thermionic emission
• Field electron emission, emission of electrons induced by an electrostatic field

• Exoelectron emission, a weak electron emission, appearing only from pretreated objects
• Photoelectric effect, the emission of electrons when electromagnetic radiation, such as light, hits a material

• Positron emission, (of a positron or "antielectron") is one aspect of β+ decay
• Electron excitation, the transfer of an electron to a higher atomic orbital