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. This process requires a wavefunction overlap between the donor and acceptor, which means it can only occur at short distances; typically within 10 Å. The excited state may be exchanged in a single step, or in two separate charge exchange steps.

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

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

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

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