NON-EQUILIBRIUM PRODUCT DISTRIBUTIONS OBSERVED IN THE ``MULTIPLE COLLISION'' CHEMILUMINESCENT REACTION $Sc + NO_{2} + Ar \to ScO^{*} (B^{2}\Sigma^{+}) + NO + $Ar

Abstract

The chemiluminescent reaction of scandium with $NO_{2}$ has been studied as a well controlled function of en argon buffer gas concentration $(P_{N}o \sim 10\mu, P_{AM} = 10\mu - 1000\mu)$. Variation of the argon background pressure leads to the observation of non-equilibrium product state distributions in the $B^{2}\Sigma^{+}$ state of ScO. These non-equilibrium distributions are caused by rapid ($\geq$ gas kinetic) energy transfer from a longer-lived excited electronic state into the $B^{2}\Sigma^{+}$ $state.^{2}$ A simple perturbation analysis of the pressure dependence of the spectroscopic features which characterize the rapid energy transfer routes allows one to deduce the energy transfer rate and the magnitude of mixing between the $B^{2}\Sigma^{+}$ state and the state from which transfer $occurs.^{1}$ The current experimental results are compared with the emission spectra obtained for the nascent $ScO^{*} (B^{2}\Sigma^{+})$ product formed in the bimolecular ``single collision’’ process Sc + $NO_{2} \rightarrow ScO^{*} + NO_{2}$.