Yield and decay of the hydrated electron from 100 ps to 3 ns

Energy is deposited by fast electrons in water in small localized volumes called spurs. The decay of the hydrated electron in a spur has been measured to be about 17 percent between 100 ps and 3 ns. Half of this decay occurs before 700 ps where previous techniques could not observe any decay. The principal reactions of the hydrated electron in the spur are presumed to be e-/sub aq/ + e-/sub aq/, e-/sub aq/ + H+, and e-/sub aq/ + OH. Scavengers for the hydrogen ion are about equally effective in slowing the decay as are scavengers for the hydroxyl radical except for OH- which seems unusually effective. This suggests H+ and OH are distributed similarly with respect to e-/sub aq/. Spur decay is also observed for the products of electron capture, Cd+ or RSSR-, where RSSR is cystamine. The observations reconcile different methods for measurement of the initial hydrated electron yield to 4.6 +- 0.2 molecules/100 eV, and combined with our earlier data, provide the major features of the history of e-/sub aq/ in the spur from 100 ps to the achievement of a homogeneous distribution