Kinetics of gas phase ion–ion recombination in NO++X–→ NO+X for X being chlorine, bromine and iodine

Abstract

The rate coefficient k₁ for the gas phase recombination of NO⁺ with halide ions X^– in NO⁺+ X^–→ NO + X has been measured in flames of C₂H₂+ O₂+ N₂ over the temperature range 2200 to 2650 K. Chlorine, bromine and iodine have been used as X. All k₁ values are in the range 0.8–2.1 × 10^–8 ion^–1 cm³ s^–1, corresponding to cross-sections (πσ²) of ∼10^–17 m². For each halogen, k₁ has a negative temperature coefficient. Also at any one temperature, k₁ is largest for X being chlorine and smallest for iodine. In general, these measurements are in agreement with Olson's “absorbing sphere” model for ion–ion recombination.