Kinetic and spectroscopic analysis of NH3 decomposition under R.F. Plasma at moderate pressures

The plasma decomposition of NH₃ has been studied as a function of the residence time, power input, and pressure. The process follows apparently zero-order kinetics, which can be interpreted on the basis of a kinetic mechanism involving as initial step the rupture of an N-H bond from vibro-rotationally excited modecules. Simultaneous spectroscopic observations of the emission light due to electronically excited NH₂, NH, H, and N₂ have been used to confirm the suggested mechanism and to show that NH₂ and NH are successive intermediate species and that the final step of the decomposition process is the bimolecular recombination NH+NHN₂+H₂.