M. EBERT 



hydrogen peroxide was detected with hydrogen alone or with mixtures 

 of hydrogen and nitrogen, but with mixtures of hydrogen and oxygen, 

 hydrogen peroxide yields were higher than those obtained with oxygen alone. 

 Figure 3 summarizes these results. The three curves were obtained with 

 2-9 X lO^'rad, 10-5 X lO^rad and 115 X lO^rad of 1 -2 MeV electrons. 



Comparison of the curves shows that the lower the dose, the smaller the 

 range of oxygen tension which influences the yield obtained. Thus at 

 2-9 X lO'^rad, the hydrogen peroxide yield no longer increased, i.e. the 

 yield became constant with oxygen concentration in the oxygen-nitrogen 

 mixtures above 12 per cent oxygen. With the highest dose, on the other 

 hand, the yield of hydrogen peroxide increased with oxygen tension up to 

 100 per cent oxygen in the mixture. The same tendency is seen in the curves 

 for hydrogen-oxygen mixtures. At the lowest dose, hydrogen peroxide 



E 



>5 



I 



I 



H2 

 N2 



% 100 75 



% 



% 25 



50 75 



- - 



50 75 WO 



25 



75 



50 

 50 



- 

 75 100 

 25 



25 

 75 



50 

 50 



75 

 25 



100 

 

 



Figure 3. Effect of gas treatment on hydrogen peroxide yield 



yields were constant over a range of 10 per cent to 90 per cent hydrogen or 

 oxygen respectively. It seems justifiable to extrapolate these results to still 

 lower doses, at which the dependence of the yield of hydrogen peroxide on 

 the amount of oxygen present (or hydrogen and oxygen in the case of 

 hydrogen-oxygen mixtures) would be critical over a very small range indeed. 

 The hydrogen peroxide yields with hydrogen-oxygen mixtures may be 

 accounted for by an increase in the concentration of hydrogen radicals 

 arising from reaction (8)^^. 



H2 + OH -^ HgO + H .... (8) 



If hydrogen is present, but no oxygen, the break-down of hydrogen peroxide 

 via reacdon (7) predominates, and the probability of reaction (4) will be 

 reduced. If oxygen is present as well as hydrogen, it \vill remove hydrogen 

 radicals by reactions (1) and (3), and the reaction rates of break-down pro- 

 cesses, (4) and (7), will be accordingly decreased. Accordingly, not only the 



33 D 



