The molecular products H2 and H2O2 may be destroyed and water is reformed by the following chain reaction:

(6–6)

(6–7)

Production of molecular O2 is brought about by the following reactions:

(6–8)

(6–9)

(6–10)

(6–11)

The O2 is destroyed mainly by the reaction:

(6–12)

Within seconds of irradiation, steady-state concentrations of molecular and radical species can be reached in a static system which contains pure water. The examples of radiolysis model calculations(21) for the production of H2, O2, and H2O2 in air-free and air-saturated water at ambient temperature are shown in Figure 6–1. In air-free water, all three radiolytic products reach steady state concentrations at ~200 Gy of total dose (Figures 6–1, A and B). In the presence of excess oxygen in water, both H2 and H2O2 increase and they may continue to increase until the oxygen is consumed to an equilibrium level (Figure 6–1, C).

The chemical yield of the decomposition product is denoted by the symbol G. The G value is defined as



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