Title: heavy atom effect
Long Title: IUPAC Gold Book - heavy atom effect
DOI: 10.1351/goldbook.H02756
Status: current

Definition
The enhancement of the rate of a spin-forbidden process by the presence of an atom of high atomic number, which is either part of, or external to, the excited molecular entity. Mechanistically, it responds to a spin–orbit coupling enhancement produced by a heavy atom.

Related Terms
- atomic number: https://goldbook.iupac.org//terms/view/A00499
- spin–orbit coupling: https://goldbook.iupac.org//terms/view/S05870

Source
- PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2245 (https://doi.org/10.1351/pac199668122223)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/H02756/html
- json: https://goldbook.iupac.org/terms/view/H02756/json
- xml: https://goldbook.iupac.org/terms/view/H02756/xml

Citation: Citation: 'heavy atom effect' 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.H02756
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Accessed: 2026-02-27T00:20:12+00:00