Title: Förster cycle
Long Title: IUPAC Gold Book - Förster cycle
DOI: 10.1351/goldbook.F02487
Status: current

Definition
An indirect method of determination of excited state equilibria, such as \(\rm{p}K^{\rm{*,a}}\) values, based on ground state thermodynamics and electronic transition energies. This cycle considers only the difference in molar enthalpy change (\(\Delta \Delta H\)) of reaction of ground and excited states, neglecting the difference in molar entropy change of reaction of those states (\(\Delta \Delta S\)).

Related Terms
- enthalpy: https://goldbook.iupac.org//terms/view/E02141
- entropy: https://goldbook.iupac.org//terms/view/E02149
- excited state: https://goldbook.iupac.org//terms/view/E02257
- ground state: https://goldbook.iupac.org//terms/view/G02704

Source
- PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2243 (https://doi.org/10.1351/pac199668122223)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/F02487/html
- json: https://goldbook.iupac.org/terms/view/F02487/json
- xml: https://goldbook.iupac.org/terms/view/F02487/xml

Citation: Citation: 'Förster cycle' 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.F02487
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Accessed: 2026-06-10T09:59:13+00:00