Electron impact dissociation of CO2 (a review)

Based on a detailed analysis and generalization of the results of calculations of the energy spectrum of electrons using different models in gas discharges in pure carbon dioxide CO2 and in mixtures containing CO2 , the rate constant of CO2 dissociation by electron impact in a gas discharge of direct current at atmospheric pressure is found. It is shown that, at values of the reduced electric field from 55 Td to 100 Td, the predominant mechanism of decomposition of the CO2 molecule is the collision of CO2 molecules with electrons. An expression is obtained for calculating the rate constant of CO2 dissociation by electron impact as a function of the reduced electric field.

Rate coefficients for electron-impact dissociation of O3+ to singly charged fragments

Rate coefficients for electron-impact dissociation of O3+ to the O+ and O2+ fragments are calculated for the new, recommended cross section data set and for various collisional conditions. Two sets of the cross section data, measured recently by different experimental groups, are used. These cross sections differ significantly with each other, but are renormalized and optimized to the coherent data base. Rate coefficients for the ozone cation fragmentation are determined using the Maxwellian and the non-thermal electron energy distribution functions (EEDF). In the case of Maxwellian distribution, mean electron energies cover the range from zero up to 2 keV. Non-thermal electron energy distribution functions are adopted from the recent electron observations by the 3-D plasma and energetic particles experiment on the WIND spacecraft. The non-thermal rates are evaluated for the mean electron energies from 4 to 80 eV. The role of the possible contribution of electron-impact dissociation of O3+ to the Ozone layer depletion has been emphasized.

Rate coefficients for electron-impact dissociation of O3+ to singly charged fragments

Rate coefficients for electron-impact dissociation of O3+ to the O+ and O2+ fragments are calculated for the new, recommended cross section data set and for various collisional conditions. Two sets of the cross section data, measured recently by different experimental groups, are used. These cross sections differ significantly with each other, but are renormalized and optimized to the coherent data base. Rate coefficients for the ozone cation fragmentation are determined using the Maxwellian and the non-thermal electron energy distribution functions (EEDF). In the case of Maxwellian distribution, mean electron energies cover the range from zero up to 2 keV. Non-thermal electron energy distribution functions are adopted from the recent electron observations by the 3-D plasma and energetic particles experiment on the WIND spacecraft. The non-thermal rates are evaluated for the mean electron energies from 4 to 80 eV. The role of the possible contribution of electron-impact dissociation of O3+ to the Ozone layer depletion has been emphasized.

Electron-Impact Dissociation of Vibrationally-Excited Molecular Hydrogen into Neutral Fragments

We present convergent close-coupling (CCC) calculations of electron-impact dissociation of vibrationally-excited molecular hydrogen into neutral fragments. This work follows from our previous results for dissociation of molecular hydrogen in the ground vibrational level [Scarlett et al., Eur. Phys. J. D 72, 34 (2018)], which were obtained from calculations performed in a spherical coordinate system. The present calculations, performed utilizing a spheroidal formulation of the molecular CCC method, reproduce the previous dissociation cross sections for the ground vibrational level, while allowing the extension to scattering on excited levels.

ON MECHANISMS OF INCREASING HCL DISSOCIATION DEGREE IN GLOW DISCHARGE PLASMA

The influence of initial compositions of the binary HCl+Ar and HCl+O2 gas mixtures on the hydrogen chloride dissociation kinetics in low temperature gas discharge plasma was investigated. The experiments were carried out under the conditions of direct current glow discharge at constant total gas pressure (100 Pa) and discharge current (25 mA). The data on electro-physical plasma parameters and plasma composition were obtained by modeling procedure based on the simultaneous solution of Boltzmann kinetic equation and the equations of chemical kinetics for neutral and charged species in a steady-state approximation. It was found that an increase in the second component fraction in both gas mixtures results in the sufficient increase in the HCl dissociation degree (aHCl = 23–43% for 0–80% Ar and 23–90% for 0–80% O2), which is associated with different mechanisms. Particularly, in the HCl+Ar gas mixture, an effect of increasing aHCl is provided by an increase in the electron impact dissociation frequency due to the change in electro-physical plasma parameters, such as electron mean energy and electron density. For the HCl+O2 gas mixture, such mechanism is almost negligible because of the weak disturbances in both electron energy distribution and formation/decay balance for charged species in the combination of two molecular electronegative gases. At the same time, the HCl dissociation kinetics in this gas system appears to be strongly dependent on the gas-phase interactions with ground state of oxygen atoms O(3P), metastable atoms O(1D) and OH radicals. It was found that the rates of corresponding processes begin to exceed the HCl electron impact dissociation rate at 20% O2 in HCl+O2.Forcitation:Efremov A.M., Murin D.B., Belyaev S.V. On mechanisms of increasing hcl dissociation degree in glow discharge plasma. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 7. P. 61-66