Kinetics of aerosol formation in irradiated gaseous NO2–SO2 mixtures

Abstract

We observe in gaseous mixtures of NO₂ and SO₂ the formation of white particles upon irradiation with 488 nm laser light and have measured the time of irradiation necessary for first detecting visually these particles at various total pressures, mole ratio of SO₂ to NO₂, and light intensities. A proposed simple reaction mechanism, up to the first reaction step of photoexcited NO₂ and SO₂, is consistent with the observations. The quenching coefficient of NO₂^* by SO₂ is 5.7×10¹³ cm³/mole sec and the coefficient of the assumed rate‐determining initial step, NO₂^*+SO₂, is 8.2×10¹⁰ cm³/mole sec.