Direct kinetics study of the CH₃C(O)O₂ + NO reaction using chemical ionization mass spectrometry

A direct measurement of the CH₃C(O)O₂ + NO gas-phase reaction rate coefficient over the temperature range 200-402 K was made using chemical ionization mass spectrometric detection of the CH₃C(O)O₂ reactant. A significant temperature dependence was observed, and a temperature dependent expression of k(T) = (8.1 ± 1.3) × 10^-12 exp{(270 ± 60)/T} cm³ molecule^-1 s^-1 was determined. The 298 K rate coefficient, k = (2.0 ± 0.3) × 10^-11 cm³ molecule^-1 s^-1, agrees well with results from previous indirect measurements. NO₂, CH₃, and CO₂ were positively identified as products originating from the reaction. The question of whether CH₃ and CO₂ are direct products of the reaction or result from the thermal decomposition of CH₃C(O)O could not be answered. The 298 K rate coefficients for the reactions of SF₆^-, I^-, and O₃^- with CH₃C(O)O₂ were measured to be (7_-2⁺⁴) × 10^-10, (9_-5⁺⁷) × 10^-10, and ≥2 × 10^-10 cm³ molecule^-1 s^-1, respectively.