Reactions of ion radical centres in melanin pigments

Electron transfer reactions between various aromatic molecules in a vitreous MTHF have been investigated in ref. 79 by the same method as in ref. 12. Reactions having free energy changes from AG° = —0.01 to — 2.75 eV have been studied. For each reaction the electron transfer rate constants, k(R), for various distances, R, between the reacting particles have been found from the reaction kinetics assuming random distribution of the 

Thus the tunneling mechanism appears to occur rather frequently in low-temperature reactions of organic anion radicals and cation radicals. 

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