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.
PAC, 1996, 68, 2223. 'Glossary of terms used in photochemistry (IUPAC Recommendations 1996)' on page 2231 (https://doi.org/10.1351/pac199668122223)