Parameter describing the apparent work function of a solid that controls the electronic current density,
\(J\), emitted from a conductor at temperature
\(T\).
\(W = -kT\ln(J/AT^{2})\), where
\(k\) is the Boltzmann constant and
\(A\) is the Richardson constant.
Notes: - For polycrystalline solids, the thermionic work function will be close to the minimum work function of the crystallites present.
- Richardson constant, \(A =(4\uppi m_{\rm{e}} k^2 e)/h^3 \approx \pu{1.202E6 A m^{-2} K^{-2}}\) where \(m_{\rm{e}}\) is the mass of the electron, \(e\) the elementary charge, and \(h\) is the Planck constant.
See also: photoelectric work function
Source:
PAC, 2020, 92, 1781. 'Glossary of methods and terms used in surface chemical analysis (IUPAC Recommendations 2020)' on page 1817 (https://doi.org/10.1515/pac-2019-0404)