Low temperature pulse radiolysis of concentrated aqueous solutions. Dry electron capture efficiencies and tunnelling processes of trapped electrons in 9.5 mol dm–3 LiCl and 10 mol dm–3 OH– solutions

Abstract

The spectra and reactions of trapped electrons produced by pulse radiolysis in 9.5 mol dm^–3 LiCl and 10 mol dm^–3 OH^–(5 mol dm^–3 NaOH + 5 mol dm^–3 KOH) solutions have been studied. In each case as the temperature is lowered the spectra of e^–_t first narrow and shift to the blue between 300 and 200 K, and then broaden and shift back of the red between 200 and 150 K.

Reactive solutes decrease G(e^–_t) and this is attributed to the capture of electrons before they become trapped. Relative capture efficiencies for a number of solutes have been calculated.

Trapped electrons react with solutes even when diffusion cannot occur. In common with other workers we attribute this to tunnelling reactions of e^–_t. However, the tunnelling rates are quite different in the two media, and the differences are rationalised in terms of a trap to trap and trap to solute tunnelling mechanism.