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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.
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]
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 ...
Chemical ionization in an atmospheric pressure electric discharge is called atmospheric pressure chemical ionization (APCI), which usually uses water as the reagent gas. An APCI source is composed of a liquid chromatography outlet, nebulizing the eluent, a heated vaporizer tube, a corona discharge needle and a pinhole entrance to 10 −3 torr ...
The DART ionization process can produce positive or negative ions depending on the potential applied to the exit electrode. This ionization can occur for species desorbed directly from surfaces such as bank notes, tablets, bodily fluids (blood, saliva and urine), polymers, glass, plant leaves, fruits & vegetables, clothing, and living organisms.
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).