What is the term used for the phenomenon when thermal energy causes electrons to be emitted from a material?

The phenomenon where thermal energy leads to the emission of electrons from a material is known as thermionic emission. This occurs when the thermal energy provided to the electrons exceeds the work function of the material, allowing them to break free from the surface. This effect is commonly observed in metals and semiconductors when heated to high temperatures, resulting in the release of electrons into the surrounding space.

In contrast, photoemission involves the ejection of electrons due to the absorption of photons, which is distinctly different from the thermal process. The Auger effect relates to the ejection of an electron following the ionization of an atom, typically by another electron rather than thermal energy. Lastly, field emission refers to the expulsion of electrons from a material due to the application of a strong electric field, rather than thermal heating. Understanding these distinctions clarifies why thermionic emission is the appropriate term for the thermal-driven electron release.