Solvent reorganization energy, electron

In Eq. (77), x = h(o/2kg T is the reduced internal frequency, q = EJhoi the reduced solvent reorganization energy, p = hElha> the reduced electronic energy gap and / (z) the modified Bessel function of order m. The quantity S is a coupling parameter which defines the contribution of the change in the internal normal mode ... 

Such a rate increase at short distances has been observed also by M.E. Michel-Beyerle [12] in time resolved experiments with a photoactivated acri-dinium ion as electron acceptor. This effect can be explained by the influence of the distance on the solvent reorganization energy The solvent reorganization energy is small for charge shifts over short distances, and it increases with the distance until it reaches a plateau. In this plateau area the solvent reorganization energy remains constant and Eq. (1) can be applied ... 

Figure 1. Activation energy of electron-transfer process as a function of electronic energy gap of a reaction. Er = Eg + Ec is the total reorganization energy where Es is the classical solvent reorganization energy and Ec is the reorganization energy of an intramolecular mode, l

Depending on the solvent polarity and redox potentials of a donor and an acceptor, the ions resulting from electron transfer may remain associated either as a contact IRP or as a solvent-separated IRP. In the contact pair, back electron transfer can take place. For such electron back-transfers, the solvent reorganization energy is less than 5% of the total reorganization energy (Serpa and Arnaut 2000). 

In general, however, solvent polarity is favorable for electron transfer. The solvent reorganization energy is particularly large for small ions in polar solvents and is usually low in low-polarity solvents. Therefore, the low polarity of a solvent cannot prevent electron transfer in all the cases when there is a significant difference between the donor ion-... 

Electron transfer (ET) reactions are analyzed by Newton in terms of continuum solvation models. Their role in the determination of the ET critical parameters (i.e. the solvent reorganization energy and the electronic coupling between the initial and final states) is analyzed using both an equilibrium and nonequilibrium solvation framework. 

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