Term: internal conversion
https://doi.org/10.1351/goldbook.I03102

Definition:
A photophysical process. An isoenenergetic radiationless transition between two electronic states of the same multiplicity. When the transition results in a vibrationally excited molecular entity in the lower electronic state, this usually undergoes deactivation to its lowest vibrational level, provided the final state is not unstable to dissociation.

Related Terms:
1) radiationless transition (http://doi.org/10.1351/goldbook.R05057).
2) electronic state (http://doi.org/10.1351/goldbook.ET07026).
3) deactivation (http://doi.org/10.1351/goldbook.D01528).
4) unstable (http://doi.org/10.1351/goldbook.U06569).
5) dissociation (http://doi.org/10.1351/goldbook.D01801).

Source: PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2248 (https://doi.org/10.1351/pac199668122223)

Citation: 'internal conversion' 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.I03102

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