Term: vertical ionization
https://doi.org/10.1351/goldbook.V06610

Definition:
A process whereby an electron is removed from a molecule in its ground or an excited state so rapidly that a positive ion is produced without change in the positions or momenta of the atoms. The resultant ion is often in an excited state.

Related Terms:
1) excited state (http://doi.org/10.1351/goldbook.E02257).

Source: PAC, 1991, 63, 1541. 'Recommendations for nomenclature and symbolism for mass spectroscopy (including an appendix of terms used in vacuum technology). (Recommendations 1991)' on page 1548 (https://doi.org/10.1351/pac199163101541)

Citation: 'vertical ionization' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.V06610

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