Charge transfer potentials correction terms

The energies of charge-transfer emission bands can be treated very similarly to the absorptions, as described in Eqs. 6-8 this is done by merely replacing the reorga-nizational terms by their negatives = eg°° - However, the substitution of electrode potentials for will also require a T sS correction if there is... 

The effect of the double layer on the kinetics is contained within the term xp[(oicn — ZQ)iFA(t>2lRT)], which is known as the Frumkin correction. It is the same for the forward and backward processes in compliance with transition state theory and the importance of the correction depends upon the magnitude and signs of olq, , Zq, and A02- If it is assumed that equilibrium prevails within the diffuse layer even when charge transfer occurs and that the diffusion layer is much thicker than the diffuse layer, then Gouy-Chapman theory can be used to calculate the dependence of 02 on the supporting electrolyte concentration (Equation (5.35)). The combination of these theoretical calculations with experimental o jE data allows the dependence of 02 on potential to be obtained, as shown in Fig. 5.9. The magnitude of A02 depends upon the position of the... 

LLUCH - The nonadditivity of the pair potentials can be responsible for the failure of Monte-Carlo and Molecular Dynamics simulations to give correct results in some studies of solvated ions. Inclusion of the polarisation term of the three-body correction is nowadays possible, although too costly in many cases. However, the most important source of error is often the lack of the charge transfer part of the many-body correction, whose incorporation is generally not evident. This is the case of the solvated proton. 

Finally, it should be noted that non-Butler-Volmer behaviour may be observed in the analysis of cyclic voltammetric data. For example, particularly in the presence of low concentrations of supporting electrolyte, electron transfer kinetics of charged species may be significantly modified due to the double layer or Frumkin effects [79]. Under these conditions, (i) the potential experienced by the reactant at the point of closest approach to the electrode can be different from the applied potential, and (ii) an additional energy barrier for the approach of charged reactants to the electrode may exist. Corrections to account for Frumkin effects have been proposed. Deviations from Butler-Volmer behaviour may also be interpreted in terms of the Marcus theory [80]. A further interesting case of non-Butler-Volmer voltammetric characteristics is observed with semiconducting elecfrode materials [81]. 

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