Photoinduced electron transfer
Photoinduced electron transfer (PET) is an excited state electron transfer process by which an excited electron is transferred from donor to acceptor.[1][2] Due to PET a charge separation is generated, i.e., redox reaction takes place in excited state (this phenomenon is not observed in Dexter electron transfer).
Breadth
Such materials include
Process
It is common to describe where electrons reside as
- Photoinduced oxidation
- [MLn]2+ + hν → [MLn]2+*
- [MLn]2+* + donor → [MLn]+ + donor+
- Photoinduced reduction
- [MLn]2+ + hν → [MLn]2+*
- [MLn]2+* + acceptor → [MLn]3+ + acceptor−
The end result of both reactions is that an electron is delivered to an orbital that is higher in energy than where it previously resided. This is often described as a charge separated electron-hole pair when working with
In the absence of a proper electron donor or acceptor it is possible for such molecules to undergo ordinary
Subsequent processes
In many photo-productive systems this charge separation is kinetically isolated by delivery of the electron to a lower energy conductor attached to the p/n junction or into an electron transport chain. In this case some of the energy can be captured to do work. If the electron is not kinetically isolated thermodynamics will take over and the products will react with each other to regenerate the ground state starting material. This process is called recombination and the photon's energy is released as heat.
- Recombination of photoinduced oxidation
- [MLn]+ + donor+ → [MLn]2+ + donor
Potential induced photon production
The reverse process to photoinduced electron transfer is displayed by
References
- ^ "Highlights of the spectroscopy, photochemistry and electrochemistry of [M(CO)4(α-diimine)] complexes, M=Cr, Mo, W" Antonín Vlcek Coord. Chem. Rev. 230 (2002) 225-242.
- ISBN 0-8247-0174-7