Radiolysis of air and nitrogen–oxygen mixtures with intense electron pulses: determination of a mechanism by comparison of measured and computed yields

Abstract

Air and other mixtures of nitrogen and oxygen containing from 0.1 to 100% oxygen have been irradiated with single, 0.12 Mrad electron pulses at a dose rate of 2 × 10²⁶ eV g⁻¹s⁻¹. The major product formed in these irradiations is ozone. For air from 400–1500 Torr, G(O₃) = 10.3 ± 0.5, the addition of SF₆ reduces this by 5.8 ± 0.5 G units. The yield of ozone from other nitrogen–oxygen mixtures varies with the concentration of oxygen. At both 700 and 1500 Torr total pressure for 1 Torr of O₂, G(O₃) ≈ 4. This increases with oxygen concentration to a maximum of G(O₃) = 12.8 for pure oxygen. For all the above conditions the yield of nitrogen dioxide is below the limits of detection.A mechanism is proposed based on known possible ionic and neutral reactions and their rate constants. Detailed computer calculations using this mechanism give results which compare well with the experimental yields. These results are consistent with an assumed yield of G(N) = 6 from processes involving neutral species in the radiolysis of pure nitrogen.