NH₂ radical formation by ammonia pyrolysis in a temperature range of 800-1000 K

The NH₂ radical absolute concentrations were measured using intracavity laser absorption spectroscopy during the process of ammonia pyrolysis at relatively low temperatures of 800-1000 K. The NH₂ spectra have been recorded at pressure of 12-380. The observed absolute concentrations (in the order of ∼ 10¹¹ molecules/cm³) were higher than was predicted by the gas-phase pyrolysis mechanisms. These mechanisms also overestimate the activation energy of the process. The experimental observations can be explained by the existence of an additional channel of NH₂ formation - probably on the surface of the reaction vessel. The addition of oxygen to the reaction mixture causes a considerable (∼ four-fold) increase in the NH₂ radical concentration.