Kinetics of the O(3P) + N2O Reaction. 1. Direct Measurements at Intermediate Temperatures

Rate coefficients for the consumption of O atoms by their reaction with N2O have been measured, at pressures from 130 to 500 mbar, using the high-temperature photochemistry technique. These represent the first direct measurements of k values of the reaction. The ground-state oxygen atoms were produced by laser photolysis of SO2, or by flash photolysis of either SO2 or O2, and monitored by time-resolved resonance fluorescence. The results yield k(1075−1140 K) = 3.2 × 10-11 exp(−9686K/T) cm3 molecule-1 s-1 with 2σ precision limits of ±12% and corresponding 2σ accuracy limits of ±26%. Results from several sources in the literature indicate a high sensitivity of the O + N2O reaction system to traces of H2O, which increases the rates if present as a contaminant. For this reason, possible effects of traces of H2O on the results were modeled. Simulated decay curves with a hypothetical H2O contaminant were used as a test of the experimental data reduction procedures. Although the concentration of H2O needed to si...