Electron capture ionization
Encyclopedia
Electron capture ionization is the ionization of a gas phase atom
or molecule
by attachment of an electron
to create an ion of the form A–•. The reaction is
where the M over the arrow denotes that to conserve energy
and momentum
a third body is required (the molecularity
of the reaction is three).
Electron capture can be used in conjunction with chemical ionization
.
An electron capture detector
is used in some gas chromatography systems.
Atom
The atom is a basic unit of matter that consists of a dense central nucleus surrounded by a cloud of negatively charged electrons. The atomic nucleus contains a mix of positively charged protons and electrically neutral neutrons...
or molecule
Molecule
A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge...
by attachment of an electron
Electron
The electron is a subatomic particle with a negative elementary electric charge. It has no known components or substructure; in other words, it is generally thought to be an elementary particle. An electron has a mass that is approximately 1/1836 that of the proton...
to create an ion of the form A–•. The reaction is
where the M over the arrow denotes that to conserve energy
Energy
In physics, energy is an indirectly observed quantity. It is often understood as the ability a physical system has to do work on other physical systems...
and momentum
Momentum
In classical mechanics, linear momentum or translational momentum is the product of the mass and velocity of an object...
a third body is required (the molecularity
Molecularity
Molecularity in chemistry is the number of colliding molecular entities that are involved in a single reaction step. While the order of a reaction is derived experimentally, the molecularity is a theoretical concept and can only be applied to elementary reactions...
of the reaction is three).
Electron capture can be used in conjunction with chemical ionization
Chemical ionization
Chemical ionization is an ionization technique used in mass spectrometry. Chemical ionization is a lower energy process than electron ionization. The lower energy yields less fragmentation, and usually a simpler spectrum...
.
An electron capture detector
Electron capture detector
An electron capture detector is a device for detecting atoms and molecules in a gas through the attachment of electrons via electron capture ionization. The device was invented in 1957 by Dr. James E...
is used in some gas chromatography systems.