Dexter electron 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.

Schematic of Dexter electron (energy) transfer

History

This short range energy transfer process was first theoretically proposed by D. L. Dexter in 1953.[5]

Rate expression

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

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

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

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

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; 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; 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 (1953). "A Theory of Sensitized Luminescence in Solids". J. Chem. Phys. 21: 836–850. Bibcode:1953JChPh..21..836D. doi:10.1063/1.1699044.