Desorption

Desorption

Desorption (/dɪˈsɔːrpʃən/) is a phenomenon whereby a substance is released from or through a surface. The process is the opposite of sorption (that is, both adsorption and absorption), and depends on the balance between the chemical potential of the substance in the gas phase and the chemical potential of the substance in the condensed phase.

Etymology

The term "desorption" comes from the French word "désorption", which was coined by reversing the English word "adsorption".

Process

In desorption, a molecule that has been adsorbed onto a surface is released back into the gas or liquid phase. This can occur spontaneously, but can also be induced by changes in the system such as increasing temperature or decreasing pressure. The rate of desorption can be influenced by the properties of the surface, the type of molecule being desorbed, and the conditions of the gas or liquid phase.

Types of Desorption

There are several types of desorption, including thermal desorption, photodesorption, and desorption ionization. Each of these types involves different mechanisms and can be influenced by different factors.

Thermal Desorption

Thermal desorption (TD) is a method used to measure the amount of a substance that is released from a material when it is heated. This is often used in environmental analysis to determine the amount of volatile and semi-volatile organic compounds in a sample.

Photodesorption

Photodesorption is a process where molecules are desorbed from a surface as a result of the absorption of light. This is often used in space science to study the composition of the surfaces of planets and moons.

Desorption Ionization

Desorption ionization is a method used in mass spectrometry to produce ions from a sample. This can be done by bombarding the sample with a beam of atoms or ions, or by heating the sample to high temperatures.

Related Terms

• Adsorption
• Absorption
• Sorption
• Chemical potential
• Thermal desorption
• Photodesorption
• Desorption ionization

External links

• Medical encyclopedia article on Desorption
• Wikipedia's article - Desorption

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