Fine-structure effect for (e,2e) collisions

For the case of inelastic electron-atom scattering, it has been known for some time that significant spin effects may be observed even if spin-dependent forces on the projectile can be ignored. These spin effects result from the Pauli principle and this phenomenon has become known as the fine-structure effect. Recently, the question of whether or not these same types of effects should be observed for atomic ionization has been considered and the initial indications are that significant spin asymmetries can also be expected for atomic ionization if the final ion satisfies LS coupling and the final J state of the ion can be resolved. In this paper, we consider this problem for electron-impact ionization of inert gases. The theory of the fine-structure effect is presented for ionization and first-order distorted-wave results are compared with very recent experimental data

Integral Cross Sections for Electron-Zinc Scattering over a Broad Energy Range (0.01-5000 eV)

We report results from the application of our optical potential and relativistic optical potential methods to electron-zinc scattering. The energy range of this study was 0.01-5000 eV, with original results for the summed discrete electronic-state integral excitation cross sections and total ionization cross sections being presented here. When combined with our earlier elastic scattering data [Marinković et al., Phys. Rev. A 99, 062702 (2019)], and the quite limited experimental and theoretical results for those processes from other groups, we critically assemble a recommended integral cross section database for electron-zinc scattering. Electron transport coefficients are subsequently calculated for reduced electric fields ranging from 0.1 to 1000 Td, using a multiterm solution of Boltzmann's equation. Some differences with corresponding results from the earlier study of White et al. [J. Phys. D: Appl. Phys. 37, 3185 (2004)] were noted, indicating in part the necessity of having accurate and complete cross section data, over a wide energy regime, when undertaking such transport simulations.Financial support from the Ministry of Education, Science and Technological Development (Project No. OI171020) of the Republic of Serbia is also acknowledged. We thank Dr. L. Campbell for his help with some aspects of this study

Electron and Positron Scattering Cross Sections from CO\u3csub\u3e2\u3c/sub\u3e: A Comparative Study over a Broad Energy Range (0.1−5000 eV)

In this Review, we present a comparative study between electron and positron scattering cross sections from CO2 molecules over a broad impact energy range (0.1−5000 eV). For electron scattering, new total electron scattering cross sections (e-TCS) have been measured with a high resolution magnetically confined electron beam transmission system from 1 to 200 eV. Dissociative electron attachment processes for electron energies from 3 to 52 eV have been analyzed by measuring the relative O−anion production yield. In addition, elastic, inelastic, and total scattering cross section calculations have been carried out in the framework of the Independent Atom Model by using the Screening Corrected Additive Rule, including interference effects (IAM-SCARI). Based on the previous cross section compilation from Itikawa (J. Phys. Chem. Ref. Data, 2002, 31, 749−767) and the present measurements and calculations, an updated recommended e-TCS data set has been used as reference values to obtain a self-consistent integral cross section data set for the elastic and inelastic (vibrational excitation, electronic excitation, and ionization) scattering channels. A similar calculation has been carried out for positrons, which shows important differences between the electron scattering behavior: e.g., more relevance of the target polarization at the lower energies, more efficient excitation of the target at intermediate energies, but a lower total scattering cross section for increasing energies, even at 5000 eV. This result does not agree with the charge independence of the scattering cross section predicted by the first Born approximation (FBA). However, we have shown that the inelastic channels follow the FBA’s predictions for energies above 500 eV while the elastic part, due to the different signs of the scattering potential constituent terms, remains lower for positrons even at the maximum impact energy considered here (5000 eV). As in the case of electrons, a self-consistent set of integral positron scattering cross sections, including elastic and inelastic (vibrational excitation, electronic excitation, positronium formation, and ionization) channels is provided. Again, to derive these data, positron scattering total cross sections based on a previous compilation from Brunger et al. (J. Phys. Chem. Ref. Data, 2017, 46, 023102) and the present calculation have been used as reference values. Data for the main inelastic channels, i.e. direct ionization and positronium formation, derived with this procedure, show excellent agreement with the experimental results available in the literature. Inconsistencies found between different model potential calculations, both for the elastic and inelastic collision processes, suggest that new calculations using more sophisticated methods are required

A Comparative Study over a Broad Energy Range (0.1-5000 eV)

Funding Information: This study has been partially supported by the Spanish Ministerio de Ciencia e Innovación (Project PID2019-104727RB-C21) and the Spanish Ministerio de Universidades (Project PRX21/00340). Work performed at Lawrence Berkeley National Laboratory was supported by the US Department of Energy, Office of Science, Division of Chemical Sciences of the Office of Basic Energy Sciences, under Contract DE-AC02-05CH11231. M.H. was supported by the US Department of Energy Office of Science, Basic Energy Sciences under Award No. DE-SC0019482. P.L.V. acknowledges the Portuguese National Funding Agency (FCT) through Research Grants CEFITEC (UIDB/00068/2020) and PTDC/FIS-AQM/31281/2017. The work is part of COST Action CA18212 - Molecular Dynamics in the GAS phase (MD-GAS). Publisher Copyright: © 2022 American Chemical Society.In this Review, we present a comparative study between electron and positron scattering cross sections from CO2 molecules over a broad impact energy range (0.1-5000 eV). For electron scattering, new total electron scattering cross sections (e-TCS) have been measured with a high resolution magnetically confined electron beam transmission system from 1 to 200 eV. Dissociative electron attachment processes for electron energies from 3 to 52 eV have been analyzed by measuring the relative O- anion production yield. In addition, elastic, inelastic, and total scattering cross section calculations have been carried out in the framework of the Independent Atom Model by using the Screening Corrected Additive Rule, including interference effects (IAM-SCARI). Based on the previous cross section compilation from Itikawa (J. Phys. Chem. Ref. Data, 2002, 31, 749-767) and the present measurements and calculations, an updated recommended e-TCS data set has been used as reference values to obtain a self-consistent integral cross section data set for the elastic and inelastic (vibrational excitation, electronic excitation, and ionization) scattering channels. A similar calculation has been carried out for positrons, which shows important differences between the electron scattering behavior: e.g., more relevance of the target polarization at the lower energies, more efficient excitation of the target at intermediate energies, but a lower total scattering cross section for increasing energies, even at 5000 eV. This result does not agree with the charge independence of the scattering cross section predicted by the first Born approximation (FBA). However, we have shown that the inelastic channels follow the FBA's predictions for energies above 500 eV while the elastic part, due to the different signs of the scattering potential constituent terms, remains lower for positrons even at the maximum impact energy considered here (5000 eV). As in the case of electrons, a self-consistent set of integral positron scattering cross sections, including elastic and inelastic (vibrational excitation, electronic excitation, positronium formation, and ionization) channels is provided. Again, to derive these data, positron scattering total cross sections based on a previous compilation from Brunger et al. (J. Phys. Chem. Ref. Data, 2017, 46, 023102) and the present calculation have been used as reference values. Data for the main inelastic channels, i.e. direct ionization and positronium formation, derived with this procedure, show excellent agreement with the experimental results available in the literature. Inconsistencies found between different model potential calculations, both for the elastic and inelastic collision processes, suggest that new calculations using more sophisticated methods are required.publishersversionpublishe

Electron-impact excitation of the (5s25p) P1/2 2 (5s26s) S1/2 2 transition in indium: Theory and experiment

We present angle-integrated and angle-differential cross sections for electron-impact excitation of the (5s25p) 2 P1/2 -> (5s26s) 2 S1/2 transition in atomic indium. Experimental data for six incident electron energies between 10 and 100 eV are compared with predictions from semirelativistic and fully relativistic B-spline R-matrix calculations, as well as a fully relativistic convergent close-coupling model. Agreement between our measured and calculated data is, with a few exceptions, found to be typically very good. Additionally, the agreement between the present theoretical predictions is generally excellent, with the remaining small deviations being associated with the slightly different, although still very accurate, descriptions of the target structure. Agreement between the present results and an earlier relativistic distorted-wave computation.The work of K.R.H., O.Z., and K.B. was supported by the U.S. National Science Foundation under Grants No. OAC1834740 and No. PHY-1803844, and by the XSEDE supercomputer allocation Grant No. PHY-090031. The (D)BSR calculations were carried out on Stampede2 at the Texas Advanced Computing Center. The work of D.V.F. and I.B. was supported by the Australian Research Council and resources provided by the Pawsey Supercomputing Centre with funding from the Australian Government and the Government of Western Australia. F.B. and G.G. acknowledge partial financial support from the Spanish Ministry MICIU (Project No. PID2019-104727RB-C21) and CSIC (Project No. LINKA20085). This work was also financially supported, in part, by the Australian Research Council (Project No. DP180101655), the Ministry of Education, Science and Technological Development of the Republic of Serbia, and the Institute of Physics (Belgrade

Viscosity cross sections for the heavy noble gases

We have calculated viscosity cross sections for argon, krypton and xenon from zero to 1 keV using the phase shifts from our previous publication [R.P. McEachran, A.D. Stauffer, Eur. Phys. J. D 68, 153 (2014)] which presented total elastic and momentum transfer cross sections for these gases. As previously, we present simple analytic fits to our results to aid in modelling plasmas containing these atoms. By using the current results and those in reference [R.P. McEachran, A.D. Stauffer, Eur. Phys. J. D 68, 153 (2014)] the first two ‘partial cross sections’ used in the general moment method of solving the Boltzmann equation can be obtained. The agreement of our viscosity cross sections with experimentally derived results indicates the overall reliability of our calculations

Second-Order Distorted Wave Calculation for Elastic and Inelastic Electron-Sodium Scattering

Second-order distorted wave calculations are reported for elastic scattering and excitation of the 32P°, 42S, and 42P° states of sodium by 10-150 eV electrons. The second-order results are summed over bound intermediate states and integrated over continuum intermediate states to numerical convergence. The effects of atomic charge cloud polarization and exchange distortion are isolated and examined. Experimental and theoretical results are compared for differential cross sections, spin asymmetry parameters, transferred angular momentum, and triplet/singlet ratios. It is found that the second-order results are typically in reasonably good agreement with experiment for energies above about 10 eV

Low-Energy Elastic Electron Scattering from Helium Atoms

We reinvestigate a key process in electron-atom collision physics, the elastic scattering of electrons from helium atoms. Specifically, results from a special-purpose relativistic polarized-orbital method, which is designed to treat elastic scattering only, are compared with those from a very extensive, fully ab initio, general-purpose B-spline R-matrix (close-coupling) code

Second-Order Distorted-Wave Calculation for Electron-Lithium Scattering

We have performed second-order distorted-wave calculations for electron-impact elastic scattering, 2p excitation and 3s excitation of lithium. The second-order results are used to study the importance of polarization, absorption, exchange scattering and continuum channels. These results are compared with experimental measurements and other theoretical calculations. © 1994 IOP Publishing Ltd

Low-Energy Elastic Electron Scattering from Helium Atoms

We reinvestigate a key process in electron-atom collision physics, the elastic scattering of electrons from helium atoms. Specifically, results from a special-purpose relativistic polarized-orbital method, which is designed to treat elastic scattering only, are compared with those from a very extensive, fully ab initio, general-purpose B-spline R-matrix (close-coupling) code