natural lifetime

of an excited state
symbol: Δt, unit: s
https://doi.org/10.1351/goldbook.08640
Lifetime of an excited state of a molecule that is isolated from radiation fields and other molecules or entities.
Notes:
  1. The lifetime is limited by the probability of spontaneous emission to a lower state. If an excited state, n can only emit spontaneously to a single lower state m, the natural lifetime of state n equals the reciprocal of Amn, the Einstein transition probability of spontaneous emission.
  2. SI unit: s
Source:
PAC, 2021, 93, 647. (Glossary of methods and terms used in analytical spectroscopy (IUPAC Recommendations 2019)) on page 755 [Terms] [Paper]
Citation: 'natural 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.08640 RIS BibTex EndNote
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