| Abstract
| - The kinetics of the CH2I + NO2, CH2Br + NO2, and CHBrCl + NO2 reactions have been studied attemperatures between 220 and 360 K using laser photolysis/photoionization mass spectrometry. Decays ofradical concentrations have been monitored in time-resolved measurements to obtain reaction rate coefficientsunder pseudo-first-order conditions. The bimolecular rate coefficients of all three reactions are independentof the bath gas (He or N2) and pressure within the experimental range (2−6 Torr) and are found to dependon temperature as follows: k(CH2I + NO2) = (2.18 ± 0.07) × 10-11 (T / 300 K)-1.45± 0.22 cm3 molecule-1s-1 (220−363 K), k(CH2Br + NO2) = (1.76 ± 0.03) × 10-11 (T/300 K)-0.86± 0.09 cm3 molecule-1 s-1 (221−363 K), and k(CHBrCl + NO2) = (8.81 ± 0.28) × 10-12 (T/300 K)-1.55± 0.34 cm3 molecule-1 s-1 (267−363K), with the uncertainties given as one-standard deviations. Estimated overall uncertainties in the measuredbimolecular reaction rate coefficients are about ±25%. In the CH2I + NO2 and CH2Br + NO2 reactions, theobserved product is formaldehyde. For the CHBrCl + NO2 reaction, the product observed is CHClO. Inaddition, I atom and iodonitromethane (CH2INO2) or iodomethyl nitrite (CH2IONO) formations have beendetected for the CH2I + NO2 reaction.
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