Direct determination of product branching for the NH₂ + NO reaction at temperatures between 302 and 1060 K

The branching ratio of the two product channels of the NH₂ + NO reaction, α and β for the formation of N₂H + OH and N₂ + H₂O, respectively, have been determined independently at temperatures between 302 and 1060 K by mass spectrometry. For β determination, the concentration of H₂O was measured directly, whereas for α, the yield of OH was monitored by the CO₂ formed by its reaction with added CO. Both [H₂O] and [CO₂] were carefully calibrated with different standard mixtures before each measurement. α was found to increase gradually from 0.11 ± 0.02 at 302 K to 0.30 ± 0.02 at 1060 K, with the concomitant decrease of β from 0.89 ± 0.04 to 0.70 ± 0.03. The two independent measurements indicate for the first time that the relationship α + β = 1 holds quantitatively throughout the temperature range studied.