A quantum statistical analysis of the rate constant for the HO2 + NH2 reaction

The radical-radical addition reaction of NH2 with HO2 to form energised adducts, namely, NH2OOH (A) and its isomers NH2(OH)O (B) and HN(OH)2 (C) has been analysed in the framework of quantum statistical Rice-Ramsperger-Kassel theory using calculated potential energy surfaces. The contribution of the HNO formation rate constant (KB1 and KC1) to the total rate constant (KT) for the disappearance of the reactants has been examined critically. The predominant contribution to the total rate constant is the dissociation of A to NH2O. + OH. over the temperature range 300–2000 K and pressures from 0.001 to 10 atmosphere. At pressures beyond 10 atmosphere, the stabilisation rate constant of the adduct NH2OOH, KA, becomes dominant. KT remains almost constant over the whole pressure range.