No abstract

The discharge-flow technique coupled with UV-absorption spectroscopy has been used to study the production of dichlorine trioxide, Cl 2 O 3 , from the reaction between ClO and OClO radicals. The absorption cross section of Cl 2 O 3 was determined to be (1.44 AE 0.10) Â 10 À17 cm 2 molecule À1 at l max ¼ 267 nm (all errors reported are two standard deviations of the statistical error). The equilibrium constant for the process ClO þ OClO þ M Ð Cl 2 O 3 þ M was measured in the temperature range 243-298 K. A Second-Law analysis yielded values of D r H n ¼ À57.9 AE 2.1 kJ mol À1 and D r S n ¼ À132.6 AE 7.9 J K À1 mol À1. The rate coefficient for the formation of Cl 2 O 3 was measured with helium as the third body at a concentration of $7.3 AE 10 16 molecule cm À3 over the temperature range 243-283 K. Analysis of these data employing the conventional form of the rate equation for the low-pressure limit, k 0 (T) ¼ k 0 (300)Á(T/300) Àn , resulted in values of k 0 (300) ¼ (2.83 AE 0.04) Â 10 À32 cm 6 molecule À2 s À1 and n ¼ À4.32 AE 0.1. These spectroscopic, thermochemical and kinetic data are compared with previously reported values.