Ion-Pair Yield of the Tritium-Oxygen Reaction

Abstract

The rate of reaction of tritium and oxygen, initiated by the tritium beta radiation, has been investigated at 25°C, in the absence of mercury vapor, by using a sensitive Bourdon gauge as the manometer. The rate is not linear with time, but shows a small continual decrease as the reaction proceeds. The initial reaction rate was found to be directly proportional to the tritium pressure, and hence proportional to the radiation intensity. It was independent of the oxygen concentration over the range investigated. The reaction rate shows a slight dependence on the isotopic composition of the hydrogen reactant, tending to rise with increase in the mole fraction of protium. The initial reaction rate may be represented by $$R_0{\text{=1.19×10}}^{\text{−4}}{\mathrm{CT}}_2{\text{(1+0.3m}}_H\mathrm{),}$$ where Ct₂ is the tritium concentration in moles/liter or other absolute concentration units, and m_H is the mole fraction of protium in the hydrogen reactant. On the basis of a requirement of 33 ev per ion pair in the reactant mixture, the initial ion‐pair yield for tritium disappearance or water formation is (M/N)₀=3.2₅ for the reaction of pure tritium with oxygen. Material balance measurements indicate that little or no peroxide appears in the product.