A process in which under the influence of a suitable
driving force (e.g. provided by
photoexcitation) electronic charge moves without changing the difference in local charges between donor and acceptor sites.
Electron transfer reversing the charges in a system composed of a neutral donor and a cationic acceptor or of a neutral acceptor and an anionic donor provide prominent examples.
Source:
PAC, 1996, 68, 2223
(Glossary of terms used in photochemistry (IUPAC Recommendations 1996))
on page 2231