The kinetics of elementary reactions involving the oxides of sulphur IV. The formation of electronically excited sulphur dioxide on surfaces

Chemiluminescence from the reaction between O and SO has been studied in a flow system down to 10 $\mu$mHg pressure. The formation of electronically excited SO$_2$ in the $^1$B$_1$ and $^3$B$_1$ states is shown to be due to a reaction between SO and chemisorbed oxygen atoms, for which a heat of adsorption of 25-30 kcal/mole is deduced. Analysis of the spatial distribution of the visible emission yields a radiative life of (7.5 $\pm$ 2.0) x 10$^{-4}$ s for the $^3$B$_1$ state of SO$_2$.