Reaction Constants of the Hydrated Electron

Intense pulses of energetic electrons produce an absorption in the visible in aqueous solutions which is attributed to the hydrated electron, e^-_aq. By following the decay of this absorption at 5780 Å., rate constants for a number of reactions of the hydrated electron have been measured. The effect of ionic strength on the rate constant for e^-_aq + ferricyanide ion, as well as the fact that some of the added reactants are known electron scavengers, confirms that the absorption is due to e^-_aq. Among the rate constants measured are: e^-_aq + H ⁺_aq, 2.36 ± 0.24 × 10¹⁰ M^-1 sec.^-1; e^-_aq + H₂O₂, 1.23 ± 0.14 × 10¹⁰ M^-1 sec.^-1; e^-_aq + O₂, 1.88 ± 0.2 × 10¹⁰ M^-1 sec.^-1; and e^-_aq + e^-_aq, 1 × 10¹⁰ M^-1 sec.^-1; all rate constants being for – d(e^-_aq)/dt.