The distance dependence problem of non-adiabatic ET

both Ve and the associated ET rate constant, feet, should decay exponentially 

ORBITAL INTERACTIONS AND LONG-RANGE ELECTRON TRANSFER 

In summary, the distance dependence of electron transport dynamics varies as r p, where r is the bridge length (or the number of bridge units in the case of a charge hopping process) and p is less than 2. Consequently, electron transport rates display a very weak dependence on bridge length. 

If the energy gaps between the bridge and chromophore states are large (i.e., several eV), as is the case for bridges comprising saturated hydrocarbon moieties, 

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