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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 .
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.
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]
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 ...
Ionization energy is positive for neutral atoms, meaning that the ionization is an endothermic process. Roughly speaking, the closer the outermost electrons are to the nucleus of the atom, the higher the atom's ionization energy. In physics, ionization energy is usually expressed in electronvolts (eV) or joules (J).
In electromagnetism, the Townsend discharge or Townsend avalanche is an ionisation process for gases where free electrons are accelerated by an electric field, collide with gas molecules, and consequently free additional electrons. Those electrons are in turn accelerated and free additional electrons.
Chemical ionization (CI) is a soft ionization technique used in mass spectrometry. [ 1 ] [ 2 ] This was first introduced by Burnaby Munson and Frank H. Field in 1966. [ 3 ] This technique is a branch of gaseous ion-molecule chemistry. [ 2 ]
The electron is then ejected from this excited state and not from the ground state, as happens for the one-photon ionization. This ionization mode started to be used already from the 1980sin order to characterize chemically the final DNA lesions (single and double strand breaks, 8-oxo-7,8-dihydroguanine,..), stemming from this process. [39]