Title: fluence
Long Title: IUPAC Gold Book - fluence
DOI: 10.1351/goldbook.F02448
Status: current
Index: quantity

Definition
At a given point in space, the radiant energy incident on a small sphere divided by the cross-sectional area of that sphere. It is used in photochemistry to specify the energy delivered in a given time interval (for instance by a laser pulse).

Related Terms
- dose: https://goldbook.iupac.org//terms/view/DT07361
- laser: https://goldbook.iupac.org//terms/view/L03459
- photochemistry: https://goldbook.iupac.org//terms/view/P04588
- photon fluence: https://goldbook.iupac.org//terms/view/P04634
- radiant energy: https://goldbook.iupac.org//terms/view/R05039

Sources
- Green Book, 2nd ed., p. 31 (https://goldbook.iupac.org/files/pdf/green_book_2ed.pdf)
- ISO 31-05: 1992 (https://www.iso.org/iso/catalogue_detail.htm?csnumber=3635)

Related Reference
- PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2242 (https://doi.org/10.1351/pac199668122223)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/F02448/html
- json: https://goldbook.iupac.org/terms/view/F02448/json
- xml: https://goldbook.iupac.org/terms/view/F02448/xml

Citation: Citation: 'fluence' 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.F02448
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Accessed: 2026-08-08T08:23:08+00:00