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Dexter electron transfer (also called Dexter electron exchange and Dexter energy transfer) is a
fluorescence Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, ...
quenching mechanism in which an excited
electron The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary partic ...
is transferred from one
molecule A molecule is a group of two or more atoms held together by attractive forces known as chemical bonds; depending on context, the term may or may not include ions which satisfy this criterion. In quantum physics, organic chemistry, and bio ...
(a
donor A donor in general is a person, organization or government which donates something voluntarily. The term is usually used to represent a form of pure altruism, but is sometimes used when the payment for a service is recognized by all parties as rep ...
) to a second molecule (an
acceptor Acceptor may refer to: * Acceptor (accounting), the addressee of a bill of exchange * In the Indian Contract Act of 1872, the acceptor is the person to whom a proposal is made, and who has communicated his or her acceptance of the said proposal ...
) via a non radiative path. This process requires a
wavefunction A wave function in quantum physics is a mathematical description of the quantum state of an isolated quantum system. The wave function is a complex-valued probability amplitude, and the probabilities for the possible results of measurements ma ...
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.


History

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


Rate expression

The Dexter energy transfer rate, k_, is indicated by the proportionality :k_ \varpropto J \mathrm\left \frac \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_(\lambda) \, \epsilon_(\lambda) \, \lambda^4 \, d\lambda


See also

*
Fluorescence Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore a lower photon energy, ...
*
Quenching In materials science, quenching is the rapid cooling of a workpiece in water, oil, polymer, air, or other fluids to obtain certain material properties. A type of heat treating, quenching prevents undesired low-temperature processes, such as ...
*
Förster resonance energy transfer Förster resonance energy transfer (FRET), fluorescence resonance energy transfer, resonance energy transfer (RET) or electronic energy transfer (EET) is a mechanism describing energy transfer between two light-sensitive molecules (chromophores). ...
* Surface energy transfer


References

Atomic physics Fluorescence {{spectroscopy-stub Energy transfer