Activation free solvent reorganisation

Figure 11.25. Photocurrent dependence on the Gibbs free energy of electron transfer for the photo-oxidation of ferrocene derivatives (a) and photoreduction of quinone-type molecules (h) at the water/DCE interface. AG ( is evaluated from Equation (11.47), employing the formal redox potentials summarised in Table 11.1 and the applied Galvani potential difference. A deconvolution of the photocurrent relaxation in the presence of the electron acceptors was performed in order to estimate the flux of election injection g. The second-order rate constant for the photoninduced heterogeneous electron transfer is also calculated assuming values of 1 nm for dec and 5 x 10 s for A ,. The trends observed in both set of data were rationahsed in terms of a single solvent reorganisation energy and activation-less limit for the rate constant. Reprinted with permission from refs.[101] and [60]. Copyright (2002/2003) American Chemical Society.

Figure 8.3 Three-step mechanism for proton-transfer reactions of oxygen and nitrogen acids. Line I chemical species and processes, charges are omitted. Line 2 R are the reactants I is the precursor intermediate complex 1 is the successor intermediate complex P are the products t means activated complex. Line 3 a is the association to I pt is the proton-transfer d is the dissociation of I to products, b, c are the bonding and solvent reorganisation. Line 4 free-energy changes.

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