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 pressures of 12-380 Torr. The observed absolute concentrations (in the order of - 10(11) molecules/cm(3)) 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.