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Electron ionization. Electron ionization (EI, formerly known as electron impact ionization [1] and electron bombardment ionization [2]) is an ionization method in which energetic electrons interact with solid or gas phase atoms or molecules to produce ions. [3] EI was one of the first ionization techniques developed for mass spectrometry. [4]
The electron binding energy derives from the electromagnetic interaction of the electron with the nucleus and the other electrons of the atom, molecule or solid and is mediated by photons. Among the chemical elements, the range of ionization energies is from 3.8939 eV for the outermost electron in an atom of caesium to 11.567617 keV for the ...
The nth ionization energy of an atom is the energy required to detach its nth electron after the first n − 1 electrons have already been detached. Each successive ionization energy is markedly greater than the last. Particularly great increases occur after any given block of atomic orbitals is exhausted of electrons. For this reason, ions ...
Adiabatic ionization is a form of ionization in which an electron is removed from or added to an atom or molecule in its lowest energy state to form an ion in its lowest energy state. [ 16 ] The Townsend discharge is a good example of the creation of positive ions and free electrons due to ion impact.
[1] This is the minimum electron energy that produces an ion. [2] In photoionization , it is the minimum photon energy of a photon that produces some ion signal. For example, the indene bromide ion (IndBr+) only loses bromine at an incident photon energy of 10.2 eV, so the product, indenyl, has an appearance energy of 10.2 eV.
The chemical ionization process generally imparts less energy to an analyte molecule than does electron impact (EI) ionization, resulting in less fragmentation [2] and usually a simpler spectrum. The amount of fragmentation, and therefore the amount of structural information produced by the process can be controlled to some degree by selection ...
Electron capture ionization (ECI) 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).
A certain amount of energy, which may be large enough, is required to remove an electron from an atom or a molecule in its ground state. [12] [13] In chemi-ionization processes, the energy consumed by the ionization must be stored in atoms or molecules in a form of potencial energy or can be obtained from an accompanying exothermic chemical change (for example, from a formation of a new ...