Kinetics of CH2OO reactions with SO2, NO2, NO, H2O and CH3CHO as a function of pressure.

Kinetics of CH2OO Criegee intermediate reactions with SO2, NO2, NO, H2O and CH3CHO and CH2I radical reactions with NO2 are reported as a function of pressure at 295 K. Measurements were made under pseudo-first-order conditions using flash photolysis of CH2I2-O2-N2 gas mixtures in the presence of excess co-reagent combined with monitoring of HCHO reaction products by laser-induced fluorescence (LIF) spectroscopy and, for the reaction with SO2, direct detection of CH2OO by photoionisation mass spectrometry (PIMS). Rate coefficients for CH2OO + SO2 and CH2OO + NO2 are independent of pressure in the ranges studied and are (3.

CH2OO Criegee biradical yields following photolysis of CH2I2 in O2.

Yields of CH2OO and CH2IO2 from the reaction of CH2I radicals with O2 are reported as a function of total pressure, [N2] and [O2] at T = 295 K using three complementary methods. Results from the three methods are similar, with no observed additional dependence on [O2]. The CH2I + O2 reaction has a yield of ~18% CH2OO at atmospheric pressure.