The Reaction Kinetics of Amino Radicals with Sulfur Dioxide

Abstract: Application of the laser photolysis–laser-induced fluorescence method to the reaction NH2 + SO2 in argon bath gas yields pressure-dependent, third-order kinetics which may be summarized as = (1.49 ± 0.15) × 10^−31 (/298 K) − 0.83 cm^6 molecule^−2 s^−1 over 292 – 555 K, where the uncertainty is the 95% confidence interval and includes possible systematic errors.The quenching of vibrationally excited NH2 is consistent with a high-pressure limit for NH2 + SO2 of (1.62 ± 0.25) × 10^−11 cm^3 molecule^−1 s^−1 over the temperature range 295–505 K, where again the 95% confidence interval is shown. Abinitio analysis yields a H2N – SO2 dissociation enthalpy of 73.5 kJmol−1, and comparison with RRKM theory and the exponential down model for energy transfer yields ⟨Δ⟩down = 350 cm^−1 for Ar at room temperature