INVESTIGATION OF THE GAS-PHASE KINETICS OF THE REACTION K+SO2+AR

The recombination of atomic potassium, K(4(2)S), With SO2 has been inv estigated at about 863 K, in a bath of Ar at pressures from 20 to 690 mbar. K was generated by flash photolysis of KI vapor and monitored by time-resolved resonance absorption of a D-line at 766 nm under pseudo -first-order conditions. The measured pseudo-second-order rate constan ts lie in the low-pressure and falloff regions and were fitted with an empirical RRKM expression to yield k0 = 5.9 X 10(-29) cm6 s-1 and k(i nfinity) = 6.2 X 10(-10) cm3 s-1. Error limits are discussed in the te xt. The KSO2 adduct was characterized by ab initio methods. An RRKM an alysis of k0, together with a lower limit to the equilibrium constant, yielded a K-SO2 bond strength of 190 +/- 10 kJ mol-1. k(infinity) was shown to be consistent with a simple harpoon model for electron trans fer.