An HTP kinetics study of the reaction between ground-state H atoms and NH3 from 500 to 1140 K

The H+NH3 reaction has been investigated using the high-temperature photochemistry (HTP) technique. H(1 2S) atoms were generated by flash photolysis of NH3 and monitored by time-resolved atomic resonance fluorescence with pulse counting. The rate coefficient for 660≤T≤1140 K is given by k(T)=(5.7±2.8)×10−10 exp[(−8650±410)K/T] cm3 molecule−1 s−1, where the uncertainties represent one standard deviation based on a propagation of error treatment including systematic errors. The Arrhenius plot reveals curvature between 500 and 660 K which follows the results of quantum mechanical tunneling calculations based on transition state theory and an Eckart potential.