Calculated low-energy electron-impact vibrational excitation cross sections for CO₂molecule

Abstract

Vibrational-excitation cross sections of ground electronic state of carbon dioxide molecule by electron-impact through the CO − 2 ( 2 Π u ) shape resonance is considered in the separation of the normal modes approximation. Resonance curves and widths are computed for each vibrational mode. The calculations assume decoupling between normal modes and employ the local complex potential model for the treatment of the nuclear dynamics, usually adopted for the electron-scattering involving diatomic molecules. Results are presented for excitation up to 10 vibrational levels in each mode and comparison with data present in the literature is discussed.One of the technological problems, connected with strategies for reduction of the global warming coming from the greenhouse effect produced by carbon dioxide, is represented by the capture at source and storage of the CO 2 gas, mainly based on the plasmolysis process leading to the splitting of CO 2 into CO molecules and atomic or molecular oxygen [1,2]. The efficiency of the dissociation processes is strongly determined by the vibrational activation of the molecule. Models of CO 2 plasmas, aimed to optimize and clarify this chemical conversion, have recently been constructed [3][4][5][6][7]. The main limitation of these models is the lack of information on electron-impact cross sections or rate coefficients for collisions inducing vibrational transitions in CO 2 molecules; as result modellers usually resort to estimated rates or approximate scaling-laws [6].In order to fill this void, in this Letter we present a preliminary data set of electronimpact cross sections for vibrational excitation of ground electronic state of carbon dioxide molecule useful in plasma kinetic modeling. The cross sections show two distinctive features observed experimentally: a 2 Π u shape resonance around 3.8 eV [8][9][10] and, at energies below 2 eV, an enhancement due to the presence of the 2 Σ + g symmetry virtual state [11][12][13]. Both phenomena are explained in terms of a temporary CO − 2 system. For a general review on this topics see Itikawa paper [14] and references therein.We present here the cross sections for the following process:which occurs through the formation of the shape resonance generated by the electronic state 2 Π u of the CO − 2 ion. CO 2 in its ground electronic state, X 1 Σ + g , is a linear molecule with C-O equilibrium distance R eq = 2.19 a 0 characterized by three normal modes of vibration, denoted in the following by v = (ν 1 , ν 2 , ν 3 ) and referred to, respectively, as the symmetric stretching, bending mode (doubly degenerate) and asymmetric stretching. * vincenzo

The ExoMol database: Molecular line lists for exoplanet and other hot atmospheres

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CH4 reforming with CO2 in a nanosecond pulsed discharge. The importance of the pulse sequence

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