Mechanism of formation of visible-absorbing excess electrons in crystalline ice near 273 K

In pulse radiolysis experiments a strong dependence of yield of e/sub vis//sup -/ in crystalline D/sub 2/O at temperatures near 273 K on dose per pulse has been found; thus at 244 K the initial yield increased by a factor of 9 in going from 5.3 to 0.17 krd per 40-ns pulse. This dependence is interpreted in terms of competition kinetics; the precursor of e/sub vis//sup -/ can either react with another irradiation product or can drop into a vacancy present at equilibrium concentration to form e/sub vis//sup -/. The decay kinetics of e/sub ir//sup -/ were investigated between 95 and 166 K to see if this species could be the precursor of e/sub vis//sup -/, but no definite conclusion could be reached; within this temperature range e/sub ir//sup -/ appears to react with another radiation product present at a higher concentration but at temperatures above 166 K the decay is too fast for us to follow.