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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 energy of the electron beam is typically 70 electronvolts and the ionization process typically produces extensive fragmentation of the chemical bonds of the molecule. Due to the high vacuum pressure in the ionization chamber, the mean free path of molecules are varying from 10 cm to 1 km and then the fragmentations are unimolecular processes.
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 ...
The process of gaining or losing electrons from a neutral atom or molecule is called ionization. Atoms can be ionized by bombardment with radiation , but the more usual process of ionization encountered in chemistry is the transfer of electrons between atoms or molecules.
Ionization or ionisation is the process by which an atom or a molecule acquires a negative or positive charge by gaining or losing electrons, often in conjunction with other chemical changes. The resulting electrically charged atom or molecule is called an ion .
Laser-based electrospray-based ambient ionization is a two-step process in which a pulsed laser is used to desorb or ablate material from a sample and the plume of material interacts with an electrospray to create ions. [49] For ambient ionization, the sample material is deposited on a target near the electrospray.
Chemical ionization (CI) is a lower energy process than electron ionization because it involves ion/molecule reactions rather than electron removal. [6] The lower energy yields less fragmentation, and usually a simpler spectrum. A typical CI spectrum has an easily identifiable molecular ion. [7]
Resonance electron capture [3] is also known as nondissociative EC. The compound captures an electron to form a radical anion. [4] The energy of the electrons are about 0 eV. The electrons can be created in the Electron Ionization source with moderating gas such as H 2, CH 4, i-C 4 H 10, NH 3, N 2, and Ar. [5] After the ion captures the electron, the complex formed can stabilize during ...