An updated set of electron-impact cross sections for CO₂ : untangling dissociation and application to CO₂ with Ar and N₂ admixtures

Abstract

This work proposes an updated set of electron-impact cross sections (CSs) for carbon dioxide (CO2) by quantitatively identifying CO2 dissociation within the two electronic excitation channels proposed by Phelps. In particular, the CS with energy threshold at 7 eV is considered with a 15% dissociation branching ratio and is associated with dissociation into O(1D) + CO(X), while the one with threshold at 10.5 eV is used entirely for dissociation into O(3P) + CO(a3Πr). Experimental data on CO2 dissociation rate coefficients at moderate reduced electric field (E/N), CO2 conversion efficiencies at high E/N, and electron transport coefficients for E/N∈[10−2, 103] Td are used to validate the updated set and demonstrate its completeness and consistency over a wide range of E/N. Notably, the updated CS set enables the full coupling between the electron and chemical kinetics, a feature lacking in most existing CS sets. The updated set is applied to study electron kinetics in CO2–Ar and CO2–N2 mixtures, revealing significant modifications in the electron energy distribution function and CO2 dissociation rate coefficient due to mixture composition. The updated CS set is made available at the IST-Lisbon database within LXCat.