Term: lifetime
https://doi.org/10.1351/goldbook.L03516

Definition:
The time required for the luminescence intensity to decay from some initial value to 1/e of that value (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:
1) luminescence (http://doi.org/10.1351/goldbook.L03641).
2) phase fluorimetry (http://doi.org/10.1351/goldbook.P04529).
3) phosphorimetry (http://doi.org/10.1351/goldbook.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)

Citation: 'lifetime' in IUPAC Compendium of Chemical Terminology, 5th ed. International Union of Pure and Applied Chemistry; 2025. Online version 5.0.0, 2025. https://doi.org/10.1351/goldbook.L03516

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