Dexter electron transfer

Schematic of Dexter electron (energy) transfer

Dexter electron transfer (also called Dexter electron exchange and Dexter energy transfer) is a fluorescence quenching mechanism in which an excited electron is transferred from one molecule (a donor) to a second molecule (an acceptor) via a non radiative path.^[1][2] This process requires a wavefunction overlap between the donor and acceptor,^[3] which means it can only occur at short distances; typically within 10 Å.^[4] The excited state may be exchanged in a single step, or in two separate charge exchange steps.

History

This short range energy transfer process was first theoretically proposed by D. L. Dexter in 1951.^[5]

Rate expression

The Dexter energy transfer rate, $k_{ET}$, is indicated by the proportionality

$k_{ET} \varpropto J \mathrm{exp}\left [ \frac{-2r}{L} \right ]$

where $r$ is the separation of the donor from the acceptor, $L$ is the sum of the Van der Waals radii of the donor and the acceptor, and $J$ is the spectral overlap integral defined by

$J = \int f_{\rm D}(\lambda) \, \epsilon_{\rm A}(\lambda) \, \lambda^4 \, d\lambda$

See also

• Fluorescence
• Quenching
• Förster resonance energy transfer
• Surface energy transfer

References

1. Clifford B. Murphy, Yan Zhang, Thomas Troxler, Vivian Ferry, Justin J. Martin, and Wayne E. Jones, Jr. (2004). "Probing Förster and Dexter Energy-Transfer Mechanisms in Fluorescent Conjugated Polymer Chemosensors". J. Phys. Chem. B 108 (5): 1537–1543. doi:10.1021/jp0301406.
2. Alex Adronov and Jean M. J. Fréchet (2000). "Light-harvesting dendrimers". Chem. Commun.: 1701–1710. doi:10.1039/B005993P.
3. "Dexter (electron exchange) excitation transfer". goldbook.iupac.org. Retrieved 8 July 2014.
4. "Dexter Energy Transfer". chemwiki.ucdavis.edu. Retrieved 8 July 2014.
5. D. L. Dexter (1951). "A Theory of Sensitized Luminescence in Solids". J. Chem. Phys. 21: 836–850. Bibcode:1953JChPh..21..836D. doi:10.1063/1.1699044.