Quenching of NH/ND(b1Σ+) by H2, D2 and N2 at different temperatures and pressures

Abstract

The quenching of metastable NH/ND(b¹Σ⁺) radicals by Q=N₂, H₂ and D₂ has been studied using the pulsed VUV photolysis of NH₃ for the generation, and the phosphorescence NH/ND(b¹Σ⁺→X³Σ^-) for the time resolved detection of NH/ND(b). Quenching rate constants were obtained in the temperature range 200–440 K and pressures of the bath gas N₂ or Ar were varied from 0.66 to 30 kPa. The aim of this investigation is to search for the formation of complexes and their stabilization during the quenching process. The rate constants for Q=H₂ and D₂ suggest that complexes are formed which, however, are not stabilized at Ar pressures up to about 30 kPa. The results will be discussed also with regard to sparse theoretical calculations.