A KINETIC INVESTIGATION OF THE REACTIONS NA -RANGE 207-377 K( O3 AND NAO + O3 OVER THE TEMPERATURE)

The reaction Na + O3 --> NaO + O2 was studied by the pulsed photolysis of NaCl in an excess Of O3, HCl, and N2 bath gas, followed by time-re solved laser-induced fluorescence spectroscopy of atomic Na at 589.0 n m (Na(3P-2(3/2)-3(2)S)). The rate coefficient is given by k(207 K < T < 378 K) = (1.054 +/- 0.12) x 10(-9) exp[-(963 +/- 216) J mol-1/RT] cm 3 molecule-1 s-1. The reaction between NaO and O3 was studied indirect ly by the pulsed photolysis of a higher Na oxide to produce NaO in an excess Of O3 and N2 bath gas. Ab initio calculations indicate that the precursor oxide, formed from the reaction between NaO2 and O3, was pr obably NaO3. The NaO concentration was then monitored by time-resolved chemiluminescence from the reaction NaO + O --> Na(2P,2S) + O2, where the O atoms were produced by the photolysis Of 03. The temperature de pendence of the reaction NaO + O3 --> NaO2 + O2 is given by k(206 K < T < 378 K) = (1.11 +/- 0.34) X 10(-9) exp[-(4720 +/- 580) J mol-1/RT] cm3 molecule-1 s-1. The quoted uncertainties are all 2sigma. The resul ts for both reactions, which are in excellent agreement with previous studies employing fast flow tubes, are then compared to the prediction s of long-range capture theory. Finally, the impact of these reactions on the chemistry of meteor-ablated sodium in the upper atmosphere is discussed.