Work function

The work function is the minimum energy (usually measured in electron volts) needed to remove an electron from the Fermi level in a metal to a point at infinite distance away outside the surface. The work function is generally about half the ionization energy of a free atom of the metal. For example, Caesium has ionization energy 3.9 eV and work function 1.9 eV.

See also

• free energy for the Helmholtz free energy equation, which is the thermodynamic work, note that this work is not related to electron emission and is thus not directly related to the work function.
• Electron affinity