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Jonathan Tennyson - One of the best experts on this subject based on the ideXlab platform.
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calculated cross sections for low energy Electron collision with oh
Plasma Sources Science and Technology, 2019Co-Authors: K Chakrabarti, V Laporta, Jonathan TennysonAbstract:The hydroxyl radical, OH, is an important component of many natural and technological plasmasa#13; but there is little available information on processes involving itsa#13; collisions with low-energy Electrons. Low-energy Electron collisionsa#13; with OH are studied in the framework of the R-matrix method. Potentiala#13; energy curves of some of the low lying target states of doublet anda#13; quartet symmetry which go to the O($^3$P)+H($^2$S),a#13; O($^1$D)+H($^2$S) and O($^1$S)+H($^2$S) asymptotic limits area#13; obtained for inter nuclear separations between $1-6~a_0$.a#13; Scattering calculations are performed at the OH equilibrium geometrya#13; $R_e=1.8342~a_0$ to yield cross sections for elastic scattering,a#13; Electronic excitations form the $\mathrm{X}\,^2\Pi$ ground state to the firsta#13; three excited states of $\mathrm{A}\,^2\Sigma^+$, $a\,^4\Sigma^-$, $1\,^2\Sigma^-$ a#13; symmetry and for Electron Impact Dissociation of OH. The positions a#13; and widths for negative ion resonances in the $e$--OH system are useda#13; estimate the cross section for dissociative Electron attachment to a#13; OH which is found to be significant at Electron energies about 1.5 eV.a#13;
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calculated cross sections for Electron collisions with nf3 nf2 and nf with applications to remote plasma sources
Plasma Sources Science and Technology, 2017Co-Authors: James R Hamilton, Jonathan Tennyson, Shuo Huang, Mark J KushnerAbstract:Electron Impact cross sections sets are constructed for the nitrogen trifluoride, nitrogen difluoride and nitrogen monofluoride molecules. These cross sections are based on ab initio R-matrix calculations augmented by other procedures. Cross sections are presented for elastic collisions, momentum transfer, dissociative Electron attachment, Electron Impact Dissociation, ionisation and dissociative ionisation. For NF process occurring via the metastable a and b states are also considered. A semi-empirical method of estimating the products of Electron Impact ionisation is proposed and tested for ammonia. The cross sections are extended to high energy where appropriate. The cross section set constructed is tested in a global model simulation of a low pressure, inductively coupled plasma based on a Ar/NF3/O2 initial gas mixture.
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carbon monoxide dissociative attachment and resonant Dissociation by Electron Impact
Plasma Sources Science and Technology, 2016Co-Authors: V Laporta, Jonathan Tennyson, R CelibertoAbstract:Low-energy dissociative Electron attachment and resonant Electron Impact Dissociation of CO molecule are considered. Ro-vibrationally resolved cross sections and rate coefficients for both the processes are calculated using an ab-initio model based on the low-lying resonance of CO−. Final results show that the cross sections increases very rapidly as a function of the ro-vibrational level; these cross sections should be useful for understanding kinetic Dissociation of CO in strongly non-equilibrium plasmas.
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dissociative Electron attachment and Electron Impact resonant Dissociation of vibrationally excited o 2 molecules
Physical Review A, 2015Co-Authors: V Laporta, R Celiberto, Jonathan TennysonAbstract:State-by-state cross sections for dissociative Electron attachment and Electron-Impact Dissociation for molecular oxygen are computed using ab initio resonance curves calculated with the R-matrix method. When O2 is in its vibrational ground state, the main contribution for both processes comes from the $^2\Pi_u$ resonance state of $O_2^-$ but with a significant contribution from the $^4\Sigma$ resonant state. Vibrational excitation leads to an increased contribution from the low-lying $^2\Pi_{g}$ resonance, greatly increased cross sections for both processes, and the threshold moving to lower energies. These results provide important input for models of O2-containing plasmas in nonequilibrium conditions.
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dissociative Electron attachment and Electron Impact resonant Dissociation of vibrationally excited o 2 molecules
Physical Review A, 2015Co-Authors: V Laporta, R Celiberto, Jonathan TennysonAbstract:State-by-state cross sections for dissociative Electron attachment and Electron-Impact Dissociation for molecular oxygen are computed using ab initio resonance curves calculated with the $R$-matrix method. When ${\mathrm{O}}_{2}$ is in its vibrational ground state, the main contribution for both processes comes from the ${}^{2}{\ensuremath{\Pi}}_{u}$ resonance state of ${\mathrm{O}}_{2}^{\ensuremath{-}}$ but with a significant contribution from the ${}^{4}{\ensuremath{\Sigma}}_{u}^{\ensuremath{-}}$ resonant state. Vibrational excitation leads to an increased contribution from the low-lying ${}^{2}{\ensuremath{\Pi}}_{g}$ resonance, greatly increased cross sections for both processes, and the threshold moving to lower energies. These results provide important input for models of ${\mathrm{O}}_{2}$-containing plasmas in nonequilibrium conditions.
V Laporta - One of the best experts on this subject based on the ideXlab platform.
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calculated cross sections for low energy Electron collision with oh
Plasma Sources Science and Technology, 2019Co-Authors: K Chakrabarti, V Laporta, Jonathan TennysonAbstract:The hydroxyl radical, OH, is an important component of many natural and technological plasmasa#13; but there is little available information on processes involving itsa#13; collisions with low-energy Electrons. Low-energy Electron collisionsa#13; with OH are studied in the framework of the R-matrix method. Potentiala#13; energy curves of some of the low lying target states of doublet anda#13; quartet symmetry which go to the O($^3$P)+H($^2$S),a#13; O($^1$D)+H($^2$S) and O($^1$S)+H($^2$S) asymptotic limits area#13; obtained for inter nuclear separations between $1-6~a_0$.a#13; Scattering calculations are performed at the OH equilibrium geometrya#13; $R_e=1.8342~a_0$ to yield cross sections for elastic scattering,a#13; Electronic excitations form the $\mathrm{X}\,^2\Pi$ ground state to the firsta#13; three excited states of $\mathrm{A}\,^2\Sigma^+$, $a\,^4\Sigma^-$, $1\,^2\Sigma^-$ a#13; symmetry and for Electron Impact Dissociation of OH. The positions a#13; and widths for negative ion resonances in the $e$--OH system are useda#13; estimate the cross section for dissociative Electron attachment to a#13; OH which is found to be significant at Electron energies about 1.5 eV.a#13;
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carbon monoxide dissociative attachment and resonant Dissociation by Electron Impact
Plasma Sources Science and Technology, 2016Co-Authors: V Laporta, Jonathan Tennyson, R CelibertoAbstract:Low-energy dissociative Electron attachment and resonant Electron Impact Dissociation of CO molecule are considered. Ro-vibrationally resolved cross sections and rate coefficients for both the processes are calculated using an ab-initio model based on the low-lying resonance of CO−. Final results show that the cross sections increases very rapidly as a function of the ro-vibrational level; these cross sections should be useful for understanding kinetic Dissociation of CO in strongly non-equilibrium plasmas.
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Electron Impact Dissociation cross sections of vibrationally excited he molecular ion
Plasma Physics and Controlled Fusion, 2016Co-Authors: R Celiberto, K L Baluja, R K Janev, V LaportaAbstract:Electron-Impact cross sections for the Dissociation process of vibrationally excited He molecular ion, as a function of the incident Electron energy are calculated for the dissociative transition by using the R-matrix method in the adiabatic-nuclei approximation. The potential energy curves for the involved Electronic states and transition dipole moment, also calculated with the R-matrix method, were found to be in good agreement with the results reported in literature. The vibrationally resolved Dissociation cross sections of He exhibit a resonant structure around 7 eV. The observed strong variation of the magnitude of this structure with the vibrational level is explained in terms of the overlap of initial and final (continuum) state wave functions in the Franck–Condon region.
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dissociative Electron attachment and Electron Impact resonant Dissociation of vibrationally excited o 2 molecules
Physical Review A, 2015Co-Authors: V Laporta, R Celiberto, Jonathan TennysonAbstract:State-by-state cross sections for dissociative Electron attachment and Electron-Impact Dissociation for molecular oxygen are computed using ab initio resonance curves calculated with the R-matrix method. When O2 is in its vibrational ground state, the main contribution for both processes comes from the $^2\Pi_u$ resonance state of $O_2^-$ but with a significant contribution from the $^4\Sigma$ resonant state. Vibrational excitation leads to an increased contribution from the low-lying $^2\Pi_{g}$ resonance, greatly increased cross sections for both processes, and the threshold moving to lower energies. These results provide important input for models of O2-containing plasmas in nonequilibrium conditions.
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dissociative Electron attachment and Electron Impact resonant Dissociation of vibrationally excited o 2 molecules
Physical Review A, 2015Co-Authors: V Laporta, R Celiberto, Jonathan TennysonAbstract:State-by-state cross sections for dissociative Electron attachment and Electron-Impact Dissociation for molecular oxygen are computed using ab initio resonance curves calculated with the $R$-matrix method. When ${\mathrm{O}}_{2}$ is in its vibrational ground state, the main contribution for both processes comes from the ${}^{2}{\ensuremath{\Pi}}_{u}$ resonance state of ${\mathrm{O}}_{2}^{\ensuremath{-}}$ but with a significant contribution from the ${}^{4}{\ensuremath{\Sigma}}_{u}^{\ensuremath{-}}$ resonant state. Vibrational excitation leads to an increased contribution from the low-lying ${}^{2}{\ensuremath{\Pi}}_{g}$ resonance, greatly increased cross sections for both processes, and the threshold moving to lower energies. These results provide important input for models of ${\mathrm{O}}_{2}$-containing plasmas in nonequilibrium conditions.
R Celiberto - One of the best experts on this subject based on the ideXlab platform.
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carbon monoxide dissociative attachment and resonant Dissociation by Electron Impact
Plasma Sources Science and Technology, 2016Co-Authors: V Laporta, Jonathan Tennyson, R CelibertoAbstract:Low-energy dissociative Electron attachment and resonant Electron Impact Dissociation of CO molecule are considered. Ro-vibrationally resolved cross sections and rate coefficients for both the processes are calculated using an ab-initio model based on the low-lying resonance of CO−. Final results show that the cross sections increases very rapidly as a function of the ro-vibrational level; these cross sections should be useful for understanding kinetic Dissociation of CO in strongly non-equilibrium plasmas.
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Electron Impact Dissociation cross sections of vibrationally excited he molecular ion
Plasma Physics and Controlled Fusion, 2016Co-Authors: R Celiberto, K L Baluja, R K Janev, V LaportaAbstract:Electron-Impact cross sections for the Dissociation process of vibrationally excited He molecular ion, as a function of the incident Electron energy are calculated for the dissociative transition by using the R-matrix method in the adiabatic-nuclei approximation. The potential energy curves for the involved Electronic states and transition dipole moment, also calculated with the R-matrix method, were found to be in good agreement with the results reported in literature. The vibrationally resolved Dissociation cross sections of He exhibit a resonant structure around 7 eV. The observed strong variation of the magnitude of this structure with the vibrational level is explained in terms of the overlap of initial and final (continuum) state wave functions in the Franck–Condon region.
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dissociative Electron attachment and Electron Impact resonant Dissociation of vibrationally excited o 2 molecules
Physical Review A, 2015Co-Authors: V Laporta, R Celiberto, Jonathan TennysonAbstract:State-by-state cross sections for dissociative Electron attachment and Electron-Impact Dissociation for molecular oxygen are computed using ab initio resonance curves calculated with the R-matrix method. When O2 is in its vibrational ground state, the main contribution for both processes comes from the $^2\Pi_u$ resonance state of $O_2^-$ but with a significant contribution from the $^4\Sigma$ resonant state. Vibrational excitation leads to an increased contribution from the low-lying $^2\Pi_{g}$ resonance, greatly increased cross sections for both processes, and the threshold moving to lower energies. These results provide important input for models of O2-containing plasmas in nonequilibrium conditions.
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dissociative Electron attachment and Electron Impact resonant Dissociation of vibrationally excited o 2 molecules
Physical Review A, 2015Co-Authors: V Laporta, R Celiberto, Jonathan TennysonAbstract:State-by-state cross sections for dissociative Electron attachment and Electron-Impact Dissociation for molecular oxygen are computed using ab initio resonance curves calculated with the $R$-matrix method. When ${\mathrm{O}}_{2}$ is in its vibrational ground state, the main contribution for both processes comes from the ${}^{2}{\ensuremath{\Pi}}_{u}$ resonance state of ${\mathrm{O}}_{2}^{\ensuremath{-}}$ but with a significant contribution from the ${}^{4}{\ensuremath{\Sigma}}_{u}^{\ensuremath{-}}$ resonant state. Vibrational excitation leads to an increased contribution from the low-lying ${}^{2}{\ensuremath{\Pi}}_{g}$ resonance, greatly increased cross sections for both processes, and the threshold moving to lower energies. These results provide important input for models of ${\mathrm{O}}_{2}$-containing plasmas in nonequilibrium conditions.
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rate coefficients for dissociative attachment and resonant Electron Impact Dissociation involving vibrationally excited o 2 molecules
PROCEEDINGS OF THE 29TH INTERNATIONAL SYMPOSIUM ON RAREFIED GAS DYNAMICS, 2014Co-Authors: V Laporta, R Celiberto, Jonathan TennysonAbstract:Rate coefficients for dissociative Electron attachment and Electron-Impact Dissociation processes, involving vibrationally excited molecular oxygen, are presented. Analytical fits of the calculated numerical data, useful in the applications, are also provided.
M Capitelli - One of the best experts on this subject based on the ideXlab platform.
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self consistent Electron energy distribution functions vibrational distributions Electronic excited state kinetics in reacting microwave co2 plasma an advanced model
Physics of Plasmas, 2020Co-Authors: L D Pietanza, Gianpiero Colonna, M CapitelliAbstract:An advanced model for the calculation of Electron energy distribution functions (eedfs), vibrational distributions, and Electronic excited state densities of reacting CO2 in microwave (MW) discharges has been developed for clarifying: (1) the role of Electronic states of the relevant neutral species in affecting the eedf and (2) the contribution to the CO2 Dissociation of the Electron Impact and heavy particle Dissociation mechanisms. To model the discharge, the power density typical of MW discharges is used as a parameter. Different case studies including optically thick and thin plasmas and the dependence of the CO2 Dissociation rates on the gas temperature are investigated. The results show that at a low gas temperature, i.e., 300 K, the heavy-particle Dissociation mechanism, also called the pure vibrational mechanism, prevails on the Electron Impact Dissociation one, while at a high gas temperature, i.e., 2000 K, the two mechanisms become competitive and the global behavior strongly depends on the choice of Electron Impact Dissociation cross sections. Large differences appear in the eedf, especially in the post-discharge regime, when considering thick and thin plasmas. In the thick case, a well-structured eedf appears as a result of superelastic collisions mainly involving the Electronic states of the relevant neutral species. In the thin plasma, many peaks disappear because the concentration of the excited states strongly decreases. Finally, our model gives the results of conversion and energy efficiency as well as vibrational distributions in satisfactory agreement with the corresponding results calculated by the Antwerp group.
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non equilibrium vibrational assisted Dissociation and ionization mechanisms in cold co 2 plasmas
Chemical Physics, 2016Co-Authors: L D Pietanza, G Dammando, A Laricchiuta, G Colonna, M CapitelliAbstract:Abstract Upper limits rates of pure vibrational Dissociation mechanisms of CO 2 in discharge and post discharge conditions have been compared with the direct Electron Impact rates from the ground vibrational level as well as including transitions from a multitude of vibrational states. At low reduced electric field E / N values and, mostly, in the post discharge regime ( E / N = 0), the pure vibrational rates exceed the corresponding ones from Electron Impact Dissociation mechanisms, showing the importance of vibrational excitation in the Dissociation of CO 2 . Comparison of ground vibrational state ionization rate with the corresponding one, which takes into account ionization transitions from excited vibrational levels, shows large difference in both discharge and post discharge conditions. The accuracy of the results largely depends on the number of vibrational levels included in the Boltzmann equation as shown by inserting, in the Boltzmann solver, all Electron–vibration transitions involving the asymmetric vibrational levels of the CO 2 molecule.
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vibrational excitation and Dissociation mechanisms of co2 under non equilibrium discharge and post discharge conditions
Plasma Sources Science and Technology, 2015Co-Authors: L D Pietanza, Gianpiero Colonna, G Dammando, A Laricchiuta, M CapitelliAbstract:Different mechanisms of CO2 Dissociation, in discharge and post-discharge conditions, have been computed by performing a parametric numerical solution of the Electron Boltzmann equation as a function of the electric field, the ionization degree and the vibrational temperatures and by considering elastic, inelastic, superelastic and Electron Electron collisions. Emphasis is given to the role of superelastic Electronic and vibrational collisions in affecting the Electron energy distribution function and relevant rates. The results show that, at low E/N values, the Dissociation rates from pure vibrational mechanism can overcome the corresponding rates of Electron Impact Dissociation. In any case, the Electron Impact Dissociation rates are largely dependent on the transitions from excited vibrational levels.
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nonequilibrium Dissociation mechanisms in low temperature nitrogen and carbon monoxide plasmas
Chemical Physics, 2014Co-Authors: M Capitelli, V Laporta, Gianpiero Colonna, G Dammando, A LaricchiutaAbstract:Abstract The role of vibrational excitation in affecting the Dissociation under discharge conditions characterized by reduced electric field E/N ⩽ 80 Td has been investigated in N 2 . The kinetic calculations have been performed using a self-consistent approach, solving at the same time the master equation for the composition and the distribution of internal states (vibrational and Electronic) and the Boltzmann equation for the Electron energy distribution function. The results show that vibrational mechanisms involving heavy particle excited states dominate Electron Impact Dissociation mechanisms involving the whole vibrational ladder for E/N E/N > 50 Td.
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nonequilibrium Dissociation mechanisms in low temperature nitrogen and carbon monoxide plasmas
Chemical Physics, 2014Co-Authors: M Capitelli, V Laporta, Gianpiero Colonna, G Dammando, A LaricchiutaAbstract:Abstract The role of vibrational excitation in affecting the Dissociation under discharge conditions characterized by reduced electric field E/N ⩽ 80 Td has been investigated in N 2 . The kinetic calculations have been performed using a self-consistent approach, solving at the same time the master equation for the composition and the distribution of internal states (vibrational and Electronic) and the Boltzmann equation for the Electron energy distribution function. The results show that vibrational mechanisms involving heavy particle excited states dominate Electron Impact Dissociation mechanisms involving the whole vibrational ladder for E/N E/N > 50 Td.
P C Cosby - One of the best experts on this subject based on the ideXlab platform.
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Electron Impact Dissociation of nitrogen
Journal of Chemical Physics, 1993Co-Authors: P C CosbyAbstract:The Electron‐Impact Dissociation of N2 to form two nitrogen atoms is observed in a crossed beam experiment at Electron energies between 18.5 and 148.5 eV. Detection of the correlated Dissociation fragments with a time and position sensitive detector permits detection of both ground and excited state fragments, but excludes interference from dissociative ionization products. The observed translational energy releases in the N2 Dissociation are consistent with preDissociation to N(2D)+N(4S) fragments as the primary Dissociation mechanism. Absolute cross sections for the Electron Impact Dissociation are measured and compared with previous measurements. Recommended values of this cross section are given for Electron‐Impact energies between 10 and 200 eV.
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Electron Impact Dissociation of oxygen
Journal of Chemical Physics, 1993Co-Authors: P C CosbyAbstract:The Electron‐Impact Dissociation of O2 to form two oxygen atoms is observed in a crossed beam experiment at Electron energies between 13.5 and 198.5 eV. Detection of the correlated Dissociation fragments with a time and position sensitive detector permits detection of both ground and excited state fragments, but excludes interference from dissociative ionization products. The observed translational energy releases in the O2 Dissociation are consistent with production of O(1D)+O(3P) fragments following Electron Impact excitation to the B 3Σu−, B’ 3Σu−, and 2 3Πu states, and production of O(3P)+O(3P) fragments from excitation to the (unresolved) c 1Σu−, A’ 3Δu, and A 3Σu+ states. Absolute cross sections for the Electron Impact Dissociation of O2 are measured.
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Electron Impact Dissociation of carbon monoxide
Journal of Chemical Physics, 1993Co-Authors: P C CosbyAbstract:The Electron‐Impact Dissociation of CO to form C and O atoms is observed in a crossed beam experiment at Electron energies between the Dissociation threshold (14 eV) and 198.5 eV. The center‐of‐mass energy released in the Dissociation of individual molecules is explicitly measured using a position and time sensitive detector for the correlated neutral fragments. The observed energy release distribution is found to be highly structured, reflecting Electron‐Impact excitation to Rydberg states converging to CO+(X 2Σ+) which predissociate to ground state atoms. Little or no Dissociation is observed from states above the first ionization limit. Total Electron Impact Dissociation cross sections, exclusive of dissociative ionization contributions, and partial cross sections for the dissociative excitation of specific CO Electronic states are presented.