Atomic resonance fluorescence and mass spectrometry for measurements of the rate constants for elementary reactions: O 3PJ+ NO2→ NO + O2 and NO + O3→ NO2+ O2

Abstract

New direct determinations of the rate constants k₁ and k₂(cm³ molecule^–1 s^–1) at 298 K are reported: O + NO₂ [graphic omitted] NO + O₂; k₁=(9.5 ± 1.1)× 10^–12, NO + O₃ [graphic omitted] NO₂+ O₂; k₂=(1.81 ± 0.13)× 10^–14. k₁ has been determined in two independent discharge flow systems, one using atomic resonance fluorescence to measure – d In[O]/dt, the other using mass spectrometry to measure – d In[NO₂]/dt, under pseudo first-order kinetic conditions.

Additionally, k₁ has been measured, using atomic resonance fluorescence, at 16 temperatures from 298 to 1055 K. The results indicate a small (negative) temperature coefficient (k₁∝T^–0.53) in this range, and least mean squares analysis of the present and previous direct data for k₁ leads to the expression, log₁₀(k₁/cm³ molecule^–1 s^–1)=(–9.758 ± 0.136)–(0.52 ± 0.05)log₁₀(T/K).