Term: pressure broadening
https://doi.org/10.1351/goldbook.08663

Definition:
Increase in the line width of a spectral line of a gas due to molecular collisions and other intermolecular interactions that reduce the lifetime of an excited state.

Note: At pressures sufficiently low that the line width is far smaller than the line wavelength, the line width increases linearly with pressure, the broadening is homogeneous and the line shape is Lorentzian.

Related Term: spectral line (http://doi.org/10.1351/goldbook.08550).
Related Term: wavelength (http://doi.org/10.1351/goldbook.08300).

Source: PAC, 2021, 93, 647. 'Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)' on page 760 (https://doi.org/10.1515/pac-2019-0203)

Citation: 'pressure broadening' 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.08663

License: The IUPAC Gold Book is licensed under Creative Commons Attribution-ShareAlike CC BY-SA 4.0 International (https://creativecommons.org/licenses/by-sa/4.0/) for individual terms.

Disclaimer: The International Union of Pure and Applied Chemistry (IUPAC) is continuously reviewing and, where needed, updating terms in the Compendium of Chemical Terminology (the IUPAC Gold Book). Users of these terms are encouraged to include the version of a term with its use and to check regularly for updates to term definitions that you are using.