Photochemistry of the Ferrocyanide Ion in Aqueous Solution: Hydrated Electron Formation and Aquation

Light absorption by the Fe(CN − ) 4− 6 ion in aqueous solution at selected wavelengths between 214 and 313 nm results in the formation of excited states which yield the reaction sequence: with φ e , the quantum yield, decreasing from 0.9 at the lowest to 0.1 at the highest wavelength. At and above 337.1 nm φ e = 0. The role of charge transfer to solvent (CTTS) intermediates in this process is demonstrated. Photoaquation according to magnified image is found to have very low, possibly zero quantum yield in this region. The role of acid‐base equilibria, e. g. magnified image and of the protonated species, in the photochemistry of cyanoferrate (II) species is discussed.