Formation Mechanism of Condensation Nuclei in Nighttime Atmosphere and the Kinetics of the SO2-O3-NO2 System

Article abstract of DOI:10.1021/j100183a011

An experimental study of condensation nuclei formation for the systen of SO2-O3-NO2-water vapor-zero grade air at 1 atm and room temperature has been conducted.In the experiments, nitrogen dioxide and ozone were mixed to generate NO3 and N2O5; the O3/NO2/NO3/N2O5 mixture and sulfur dioxide and water vapor were introduced into a specially designed sheath flow reaction vessel in which the oxidation of sulfur dioxide by NO3 and N2O5 occurred to produce condensation nuclei which were quantitatively determined.The results of several series of experiments accomplished at different concentrations of each of the reactants are presented.The correlations of observed concentrations of condensation nuclei to concentrations of sulfur dioxide, nitrogen dioxide, ozone, and water vapor are evaluated.A model of the mechanism of condensation nuclei formation in nighttime atmosphere is established.From the kinetic analysis of the experimental results, estimates are derived for the rate constants of the following reactions, SO2 + NO3 -> SO3 + NO2, k <= 4.5 x 10^-21 cm³ molecule^-1 s^-1; and SO2 + NO2 -> SO3 + N2O4, k = 9.1 x 10^-24 cm³ molecule^-1 s^-1, at 26.5 deg C, which are below the upper limit values reported previously.