Title: decay rate
Long Title: IUPAC Gold Book - decay rate
DOI: 10.1351/goldbook.D01541
Status: current

Definition
The rate at which a pollutant is removed from the atmosphere either by reaction with reactive transient species such as the $\ce{HO}$ radical, $\ce{O3}$, etc., by photodecomposition initiated by light absorption by the impurity, or by loss at the surface of aerosols, the earth, etc. The decay rate as applied to radioactive materials is related to the radioactive half-life (\(t_{1/2}\)) of the particular isotopic species A and its concentration \([A]_{t}\), at the given time (\(t\)): \[\rm{Rate}=\frac{[A]_{t}\ \ln 2}{t_{1/2}}\]

Related Term
- radioactive: https://goldbook.iupac.org//terms/view/R05077

Source
- PAC, 1990, 62, 2167. 'Glossary of atmospheric chemistry terms (Recommendations 1990)' on page 2183 (https://doi.org/10.1351/pac199062112167)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/D01541/html
- json: https://goldbook.iupac.org/terms/view/D01541/json
- xml: https://goldbook.iupac.org/terms/view/D01541/xml

Citation: Citation: 'decay rate' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. 10.1351/goldbook.D01541
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Accessed: 2026-06-20T23:10:17+00:00