Title: lifetime
Long Title: IUPAC Gold Book - lifetime
DOI: 10.1351/goldbook.L03516
Status: current
Index: quantity

Definition
The time required for the luminescence intensity to decay from some initial value to \(\frac{1}{\rm{e}}\) of that value (\(\rm{e} = 2.718\,...\)). Lifetimes can be measured by 'phase fluorimetry' (phosphorimetry) where the phase shift between the sinusoidally modulated exciting light and the emitted light is measured.

Related Terms
- luminescence: https://goldbook.iupac.org//terms/view/L03641
- phosphorimetry: https://goldbook.iupac.org//terms/view/F02416

Source
- PAC, 1984, 56, 231. 'Nomenclature, symbols, units and their usage in spectrochemical analysis-Part VI: molecular luminescence spectroscopy' on page 242 (https://doi.org/10.1351/pac198456020231)

Other Outputs
- html: https://goldbook.iupac.org/terms/view/L03516/html
- json: https://goldbook.iupac.org/terms/view/L03516/json
- xml: https://goldbook.iupac.org/terms/view/L03516/xml

Citation: Citation: 'lifetime' 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.L03516
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Accessed: 2026-05-09T06:26:11+00:00