Dissociation of CO2 by Electron Impact with the Formation of Metastable CO(a 3Π) and O(5S)

Molecular beam time-of-flight measurements show that CO2 is dissociated by electron impact to give two metastable fragments, CO(a 3Π) and O(5S). The experimental dissociation limit for production of CO(a 3Π) lies at 11.65±0.30 eV which agrees with the 11.45-eV energy of CO2 → lim eCO(a3Π)+O(3P). The excitation function for production of CO(a 3Π) shows structure which can be correlated with dissociation processes involving higher triplet states of CO and excited states of O. The cross section for formation of CO(a 3Π) has a maximum at 27±1 eV, a magnitude which is 0.4± 0.2 times the maximum cross section for CO→ lim eCO(a3Π) and probably has a value not far from 4×10−17cm2.