KINETICS AND EQUILIBRIUM-CONSTANT OF THE REVERSIBLE-REACTION CLO-REVERSIBLE-ARROW-CL2O2+M AT 295-K(CLO+M)

High yields of ClO radicals were obtained by pulse radiolysis of Cl2O/ Cl2 mixed with Ar, SF6, or CO2 as bath gases. The kinetics of ClO was studied directly by monitoring the transient absorption signals at 277 .2 nm. ClO was found to decay towards an equilibrium concentration in accordance with the reversible reaction ClO + ClO + M reversible Cl2O2 + M. The rate constants of the forward and reverse reactions were der ived by computer modelling of the experimental curves. The rate consta nt of the forward reaction was found to be pressure-dependent, and the following values were obtained at a total pressure of 1 bar and with different third bodies at 295 K: K2f = (2.5 +/- 0.5) x 10(-13) (M = Ar ), (4.4 +/- 0.9) x 10(-13) (M = SF6) and (4.7 +/- 0.9) x 10(-13) (M = CO2) in units of cm3 molecule-1 s-1. Based on computer simulations of the observed relaxation kinetics a value of the equilibrium constant a t 295 K, K(eq) = (6.4 +/- 1.6) x 10(-15) cm3 molecule-1, was obtained for the SF6 and Ar systems.