normal region (for electron transfer)

Region for which the rate constants increase with increasing exergonicity of the reaction in plots relating rate constants for electron transfer, or quantities related to it, with the standard Gibbs energy for the reaction ( $Δ ET G o$ ). This region is predicted by the Marcus theory for outer-sphere electron transfer for the case of $− Δ ET G o ≤ λ$ in the Marcus equation.

Source:

PAC, 2007, 79, 293 (Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)) on page 375