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(physical chemistry)
A chemical adsorption process in which weak chemical bonds are formed between gas or liquid molecules and a solid surface.



the adsorption of substances from the surrounding medium by a liquid or solid, accompanied by the formation of chemical compounds. In a narrower sense, chemisorption is regarded as the chemical binding of a substance by the surface of a solid, or chemical adsorption.

Considerable heat is released in chemisorption: the heat of chemisorption is usually 84–126 kilojoules per mole (kJ/mole), or 20–30 kcal/mole; in some cases—for example, the chemisorption of oxygen on metals—it may exceed 420 kJ/mole (100 kcal/mole). Like chemical reactions, chemisorption usually requires considerable activation energy. Thus, chemisorption is accelerated when the temperature is increased (activated adsorption). Chemisorption is selective—that is, it depends on the chemical affinity of the adsorbed substance for the solid surface.

Physical methods, such as spectroscopy, electron paramagnetic resonance, nuclear magnetic resonance, electron and ion field-emission microscopy, and slow-electron diffraction, are used to study chemisorption. The process plays an important role in heterogeneous catalysis, gas purification, and vacuum technology.


See references under ADSORPTION.


References in periodicals archive ?
The X-Ray diffraction patterns of original, activated and chemisorbed ash samples from the 1st and 4th ESP are presented in Figures 1 and 2, respectively.
1] for carboxyl (COOH) stretch vibration, (42), (43) indicate that most dodecanoic acid molecules have been chemisorbed on the surface and form salts with the metal or metal oxide.
In an unbaked metal chamber with metal seals and sufficient pumping, it is possible to remove most gas molecules except the chemisorbed water on the chamber walls.
In the case of a chemisorbed anti-wear mechanism when the mixed or boundary lubrication takes place, the temperature will increase and both AW and EP additives can react with the metal surface forming tribochemical reaction layers (iron phosphites, sulfides, sulfates, oxides and carbides--depending on the additive's chemistry) that will prevent a direct contact between the sliding metal surfaces.
The papers include an introduction to stimuli-responsive macromolecules and polymeric coatings and also cover synthetic aspects of stimuli-responsive polymers, including controlling chain topology, synthesizing terminally functionalized (co)polymers, synthesizing and applying polyelectrolyte brushes and polymer grafted layers, and tailoring thin polymer films chemisorbed into conducted surfaces by electrografting).
The terms chemisorption or chemisorbed layer are often used to describe the section remaining dominant for the next 10 to 20 molecular layers.
The Lopinski group demonstrated that chlorination of n-type H/Si(111) surfaces leads to a significant increase in the surface conductivity that can be attributed to the formation of a minority carrier channel resulting from the electron withdrawing nature of the chemisorbed chlorine.
All carbon blacks have some level of chemisorbed oxygen complexes (carboxylic, phenolic, quinonic, or lactonic groups), or volatile content, on their surfaces.
The silanol then reacts with the hydroxyl group of the fiber, forming stable covalent bonds to the cell wall that are chemisorbed onto the fiber surface (121).
It is reported that some HALS compounds are chemisorbed on the pigment surface under losing its free radical scavenging ability.
This in turn can release chemisorbed sulfur (for example in the form of CaS) to stack gas as S[O.