The temperature dependence of the bimolecular channels of the ClO + ClO reaction over the range T = 298-323 K

Abstract

The bimolecular channels of the ClO self-reaction, although negligible under stratospheric conditions, become significant above ambient temperature. The kinetics of two of the three bimolecular channels of the ClO self-reaction, ClO + ClO → Cl 2 + O 2 (1b) and ClO + ClO → OClO + Cl (1d), were studied at T = 298-323 K and at ambient pressure (p atm ≈ 760 ± 10 Torr). Radicals were generated via laser photolysis and monitored using UV absorption spectroscopy. The inclusion of charge-coupled device (CCD) detection allowed broadband monitoring of the radicals of interest along with the temporal resolution of their concentrations. Accurate and unequivocal quantification of the structured absorbers (ClO and OClO) was obtained via differential fitting procedures. The Arrhenius expressions obtained are k 1b = 2.9 -1.8+4.4 × 10 -14exp[-(283 ± 282)/T] cm 3 molecule -1 s -1 and k 1d = 7.2 -6.1+39 × 10 -15exp[-(225 ± 574)/T] cm 3 molecule -1 s -1, where the errors are 1Ï. The temperature dependences obtained in this work for both channels monitored are considerably less pronounced than those reported by Nickolaisen et al. © 2012 Wiley Periodicals, Inc.