ESR Study of the Kinetics of the Reactions of D Atoms and O Atoms with NH3

Abstract

A wide temperature‐range study using ESR atom detection has beem employed to measure the rates of the reactions of D atoms and O atoms with NH₃. In the case of the deuterium reaction, evidence is presented which shows that the interaction with NH₃ proceeds via an exchange process of the type: D+NH₃→NH₃D+H. This reaction was studied over the temperature range of 423–741°K. The specific rate constant for this exchange reaction was found to be ${\text{1.9\hspace{0.17em}±\hspace{0.17em}0.2\hspace{0.17em}×\hspace{0.17em}10}}^{13}\exp \text{(−\hspace{0.17em}10 100\hspace{0.17em}±\hspace{0.17em}150\hspace{0.17em}/\hspace{0.17em}RT)}$ in units of cubic centimeters mole⁻¹·second⁻¹. The reaction of O atoms with NH₃ was studied over the temperature interval of 361–677°K. The specific rate constant obtained for the reaction O+NH₃→OH+NH₂ was found to be ${\text{4.0\hspace{0.17em}±\hspace{0.17em}0.9\hspace{0.17em}×\hspace{0.17em}10}}^{12}\exp \text{(−\hspace{0.17em}6600\hspace{0.17em}±\hspace{0.17em}130\hspace{0.17em}/\hspace{0.17em}RT)}$ in units of cubic centimeters mole⁻¹·second⁻¹. This Arrhenius pre‐exponential factor depends on a stoichiometric factor of 3.50 atoms per NH₃ molecule assumed from other work.