Observation of NH(a 1Δ, v=1) from the H+N3 reaction

The observation and preliminary characterization, in a molecular beam scattering experiment, of the NH(a 1Δ) product from the reaction of hydrogen atoms with the azide radical, H(2S)+N3(X̃ 2Πg)→NH+N2(X 1Σ+g), are reported. Three electronic states of NH are energetically accessible [X 3Σ−, a 1Δ, b 1Σ+] in this reaction. The N3 radical was generated by reacting hydrazoic acid with fluorine atoms in a discharge-flow prereactor. A beam of hydrogen atoms was generated by a microwave discharge source using an extended Evenson–Broida cavity in a differentially pumped chamber. The NH(a 1Δ) product was detected in its v=1 level by laser fluorescence excitation in the c 1Π←a 1Δ (0,1) band. The nascent NH(a 1Δ,v=1) rotational distribution was parametrized by a Boltzmann form, and the distribution was fit to a ‘‘temperature’’ of 750±100 K. No Λ doublet specificity was observed in the NH(a 1Δ) product from our experiments.