Abstract
The dissociative electron–ion recombination processes of CO+2(X̃ 2Πg:0,0,0) has been studied by observing the CO(A 1Π–X 1Σ+) emission in the He and Ar afterglows. It was found that the CO(A:v′=0–2) states are formed in the dissociative recombination of CO+2(X̃:0,0,0) with electrons at thermal energy. The rovibrational distribution of CO(A) was N0:N1:N2=100:(T0=1000±100 K), 58±4(T1=700±50 K), and 9±2 (T2=400±100 K). The average fractions of total energy channeled into vibration and rotation of CO(A) and relative translation of the products were determined to be 〈fv〉=22%±2%, 〈fr〉=20%±2%, and 〈ft〉=58%±4%. The observed rovibrational distributions were in disagreement with statistical prior distributions, indicating that the reaction dynamics is not governed by the statistical theory. A comparison of the present results with the previous photodissociation data suggested that the CO(A:v′=0,1) states are formed through predissociation of near-resonant intermediate CO2** states coupled with a bent valence state, while the CO(A:v′=2) state is produced through predissociation of CO2** states just above the CO+2(X̃:0,0,0) state. The low CO(A:v′=2) population can be explained by the energetic constraint for thermal electrons plus CO+2(X̃:0,0,0) and/or a competition between predissociation and autoionization of CO2** states just above the CO+2(X̃:0,0,0) energy.
Published Version
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