Term: Dexter excitation transfer (electron exchange excitation transfer)
https://doi.org/10.1351/goldbook.D01654

Definition:
excitation transfer occurring as a result of an electron exchange mechanism. It requires an overlap of the wavefunctions of the energy donor and the energy acceptor. It is the dominant mechanism in triplet-triplet energy transfer. The transfer rate constant, kET, is given by: \[k_{\text{ET}}\propto \frac{h}{2\ \pi }\ P^{2}\ J\ \text{e}^{\frac{-2\ r}{L}}\] where r is the distance between donor (D) and acceptor (A), L and P are constants not easily related to experimentally determinable quantities, and J is the spectral overlap integral. For this mechanism the spin conservation rules are obeyed.

Related Terms:
1) radiative energy transfer (http://doi.org/10.1351/goldbook.R05063).
2) excitation transfer (http://doi.org/10.1351/goldbook.E02256).
3) triplet-triplet energy transfer (http://doi.org/10.1351/goldbook.T06506).
4) rate constant (http://doi.org/10.1351/goldbook.O04322).
5) spectral overlap (http://doi.org/10.1351/goldbook.S05818).

Source: PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2235 (https://doi.org/10.1351/pac199668122223)

Citation: 'Dexter excitation transfer (electron exchange excitation transfer)' 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.D01654

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