# The similarities and differences between electron transfer and charge transfer [closed]

Please explain the similarities and differences among electron transfer,electron transport, charge transfer, and charge transport from the molecular, atomic and electronic levels.

Is electron transfer different from electron transport?

Is charge transfer different from charge transport?

## closed as off-topic by Mithoron, Jan, Tyberius, M.A.R. ಠ_ಠ, Todd MinehardtSep 5 '17 at 15:54

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• I edited your question a bit, and I replaced "charge transfer" in the latter question with "charge transport" analogously with "electron transport" (it seemed like typo to me). If it wasn't the case, feel free to roll back. Also, it's a good question, but maybe you could provide some examples to make question not so broad. – andselisk Sep 5 '17 at 8:25

There is is difference between electron transfer and charge transfer. Charge transfer is usually associated with charge transfer complexes, such as TTF-TCNQ (tetrathiofulvalene-tetracyanoquinodimethane) but there are very many others. In these complexes the charge transfer from one species to the other occurs as the photon is absorbed so that the lowest excited state is $\ce{D + A + photon -> D+A-}$. This often means that these complexes are highly coloured.
In electron transfer no photon is needed and the process follows Marcus theory whereby a barrier is crossed between $\ce{D + A}$ and $\ce{D+ + A-}$, i.e. this is a thermal process with an activation barrier. The unusual feature of Marcus transfer is the that activation energy has a parabolic dependence on energy thus the rate constant can be slow in both endothermic and very exothermic conditions.