In
surface chemistry
Surface science is the study of physical and chemical phenomena that occur at the interface of two phases, including solid–liquid interfaces, solid–gas interfaces, solid–vacuum interfaces, and liquid–gas interfaces. It includes the fiel ...
, the Hertz–Knudsen equation, also known as Knudsen-Langmuir equation describes evaporation rates, named after
Heinrich Hertz
Heinrich Rudolf Hertz ( ; ; 22 February 1857 – 1 January 1894) was a German physicist who first conclusively proved the existence of the electromagnetic waves predicted by James Clerk Maxwell's Maxwell's equations, equations of electrom ...
and
Martin Knudsen
Martin Hans Christian Knudsen (February 15, 1871 in Hasmark on Funen – May 27, 1949 in Copenhagen) was a Danish physicist who taught and conducted research at the Technical University of Denmark.
He is primarily known for his study of molec ...
.
Applications
Non-dissociative adsorption (Langmuirian adsorption)
The Hertz–Knudsen equation describes the sticking of
gas
Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma).
A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...
molecules on a surface by expressing the time rate of change of the concentration of molecules on the surface as a function of the pressure of the gas and other parameters:
[R. B. Darling]
EE-527: Micro Fabrication
Virginia University (retrieved Feb. 9 2015).
:
where:
See also
*
Langmuir (unit) The langmuir (symbol: L) is a unit of exposure (or dosage) to a surface (''e.g.'' of a crystal) and is used in ultra-high vacuum (UHV) surface physics to study the adsorption of gases. It is a practical unit, and is not dimensionally homogeneous, ...
References
{{DEFAULTSORT:Hertz-Knudsen equation
Surface science