where κ el (0) and κ el (x) are the κ el values at the electrode surface (x = 0) and at a distance x from it, respectively. In the adiabatic regime of strong electronic coupling, κ el (x) → 1, which manifests itself by the independence of the rate constant on distance. At larger distances, the electronic coupling weakens, κ el (x) < 1, and even an initially adiabatic reaction becomes non-adiabatic and independent of the nuclear dynamics since κ el (x) is reduced to: 44, 46-47