THE MULTICHANNEL REACTION NH2+NH2 AT AMBIENT-TEMPERATURE AND LOW-PRESSURES

NH2 profiles were measured in a discharge flow reactor at ambient temperature by monitoring reactants and products with an electron impact mass spectrometer. At the low pressures used (0.7 and 1.0 mbar) the gas-phase self-reaction is dominated by a 'bimolecular' H-2-eliminating exit channel with a rate coefficient of k(3b)(300 K) = (1.3 +/- 0.5) x 10(-12) cm(3) molecule(-1) s(-1) and leading to N2H2 + H-2 or NNH2 + H-2. Although the wall loss for NH2 radicals is relatively small (k(w) approximate to 6-14 s(-1)), the contribution to the overall NH2 decay is important due to the relatively slow gas-phase reaction. The heterogeneous reaction yields N2H2 molecules.