Electron-transfer sensitization, representation

Figure 1. Schematic representation of electron transfer sensitization. 1 photo-oxidation of sensitizer 2 forward electron transfer (fluorescence quenching) 3 back electron transfer 4 product formation...

FIG. 4 (a) Latimer diagram of the water soluble zinc tetra-Af-methyl-4-pyridium porphyrin (ZnTMPyP ). (Reprinted with permission from Ref. 47.) (b) Schematic representation of a photosynthetic process based on porphyrin sensitized water-organic interface. Dotted line corresponds to the back electron-transfer process. (Reprinted from Ref. 51 with permission from Elsevier Science.)... 

Gerischer s distribution curves can be interpreted as representing the energy dependence of the electron transfer rate constants involving the reduced and oxidized species. Only a few electrochemical studies have attempted to evaluate the model and quantify the distributions and reorganizational parameters [17, 18]. Nevertheless, it has become common practice to draw a pictorial representation of the distributions when discussing interfacial electron transfer kinetics relevant to dye sensitization. 

Figure 16.3 shows a schematic representation of a photoelectron transfer reaction where a sensitizer (S ) in one phase is quenched by an electron donor (Q) in the adjacent phase. A charge-transfer complex [S - Q+] is formed at the inta face. In a bulk solution, recombination often occurs due to the cage effect formed by the solvent molecules. At soft interfaces, the dissociation of the charge transfer complex into photoproducts can be favored by the presence of the static electric field, and this is still a very important point to quantify in the coming years. 

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