Gas phase kinetics of the reactions of Na and NaO with O3 and N2O

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Abstract
A fast flow reactor, with an oven source and resonant fluorescence detection, was used to study the kinetics of Na atoms in the gas phase. The rate constant for Na+O3 is (7.3±1.4)×10−10 cm3 molecule−1 s−1 at 286 K and NaO+O2 is the predominant product channel. The rate constant for Na+N2O over the temperature range 240 to 429 K is (3.7±0.9)×10−10 exp[(−1690±180)/T] cm3 molecule−1 s−1. The kinetics of the NaO radical were measured directly. NaO is made in the flow tube by the reaction Na+N2O → NaO+N2 with N2O in large excess. NaO is detected by conversion to Na atoms in the detection region by NaO+NO → Na+NO2. NaO+O3 has two exothermic product channels, Na+2O2 and NaO2+O2. The rate constants are ∼5×10−11 and (1.8±0.4)×10−10 cm3 molecule−1 s−1 at 296 K, respectively. Upper limits for NaO+N2O →Na+N2+O2 and NaO+N2O → NaO2+N2 are 1×10−16 and 2×10−15 cm3 molecule−1 s−1, respectively. The rate constant for NaO+NO → Na+NO2 is ∼1.5×10−10 cm3 molecule−1 s−1. Since wall collisions remove NaO with near unit efficiency, NaO diffusion coefficients can be measured. DNaO,He =640±340 cm2 Torr s−1 and DNaO,N2O =48±24 cm2 Torr s−1 at 295 K. The error limits in all cases represent the 95% confidence level, including an estimate of systematic errors.