Measurements of the O++N2 and O++O2 reaction rates from 300 to 900 K

Rate coefficients for the O++N2 atom transfer and O++O2 charge transfer reactions are determined at thermal energies between ∼300 and ∼900 K in a heated drift tube–mass spectrometer apparatus. At 300 K the values k (O++N2)(=1.2±0.1) ×10−12 cm3/s and k (O++O2) = (2.1±0.2) ×10−11 cm3/s are obtained, with a ∼50% decrease in the reaction rates upon heating to 700 K. These results are in good agreement with heated flowing afterglow results, but the O++O2 thermal rate coefficients are systematically lower than equivalent Maxwellian rates inferred by conversion of nonthermal drift tube and flow–drift data.