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Here V is vacuum level and F is fermi level

1 Photoelectric work function

In photoelectric emission, the electron gains the kinetic energy needed to escape from photons, such an electron is called a photoelectron and the emission is called the photoelectric effect.

Photoelectric work function: φ=hf_0,

where h is Planck's constant and f_{0 is the critical frequency required for photoelectric emission.}

2 Thermionic work function

The work function is also important in the theory of thermionic emission, here the electron gains its energy from heat rather than photons. In this case, as for example that of an electron escaping from the headed negatively-charged filament of a vacuum tube, the work function may be called the thermionic work function.

3 Applications

In electronics the work function is important for design of the metal junction in Schottky diodes and for design of vacuum tubes.

The work function for most metals can be approximated as 4.5 eV.

4 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 affinityIn chemistry, electron affinity is the amount of energy absorbed when an electron is added to a neutral isolated gaseous atom to form a gaseous ion with a 1- charge. It has a negative value if energy is released. Most elements have a negative electron aff

5 External link

• http://www.pulsedpower.net/EETNTweb/Tools/Info/WorkFunctions.htm - Work functions of common metals