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Title: Low-energy elastic and inelastic scattering of electrons from SO{sub 2} using the R-matrix method

Abstract

R-matrix method is used to calculate elastic differential, integral, and momentum transfer cross sections for electron-SO{sub 2} collision. The electron-impact excitation cross sections for first seven low-lying electronic excited states of SO{sub 2} molecule from the ground state of SO{sub 2} molecule have been calculated for the first time. Sixteen low-lying electronic states of SO{sub 2} molecule are included in the close coupling expansion of the wave function of the entire scattering system, which have vertical excitation energies up to 10.51 eV. Configuration-interaction (CI) wave functions are used to calculate these excitation energies. In our CI model, we keep the core 14 electrons frozen in doubly occupied molecular orbitals 1a{sub 1}, 2a{sub 1}, 3a{sub 1}, 4a{sub 1}, 1b{sub 1}, 1b{sub 2}, 2b{sub 2} and the remaining 18 electrons span the relevant active space: 5a{sub 1}, 6a{sub 1}, 7a{sub 1}, 8a{sub 1}, 9a{sub 1}, 2b{sub 1}, 3b{sub 1}, 3b{sub 2}, 4b{sub 2}, 5b{sub 2}, 6b{sub 2}, and 1a{sub 2}. Our calculated dipole moment of the ground state of SO{sub 2} at its equilibrium geometry is 0.79 a.u., which is in reasonable agreement with the corresponding experimental value 0.64 a.u. Our calculations detect one bound SO{sub 2}{sup -} state ({sup 2}B{sub 1})more » at the equilibrium geometry of SO{sub 2} molecule. Both shape as well as core-excited shape resonances have been identified in the present work and are correlated with the experimental results on dissociative electron attachment study. A detailed analysis of resonances is provided. Cross sections are reported for the electron impact energy range 0-15 eV. All cross section calculations are performed in the fixed-nuclei approximation at the experimental equilibrium geometry of the ground state of SO{sub 2} molecule. We have also investigated dependence of resonances on the geometry of SO{sub 2} molecule to probe the possible pathways for dissociation of resulting negative ion upon electron attachment. We have excellent agreement of differential, elastic integral, and momentum transfer cross sections calculated in the 16-state R-matrix approximation with the available experimental results for electron-impact energy range 0-15 eV. Our resonant peaks correlate well with the peaks observed in the study of dissociative electron attachment (DEA) of electron with SO{sub 2} molecule.« less

Authors:
;  [1]
  1. Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India)
Publication Date:
OSTI Identifier:
20787101
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 73; Journal Issue: 4; Other Information: DOI: 10.1103/PhysRevA.73.042702; (c) 2006 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
74 ATOMIC AND MOLECULAR PHYSICS; ANIONS; APPROXIMATIONS; BOUND STATE; CONFIGURATION INTERACTION; COUPLING; CROSS SECTIONS; DIPOLE MOMENTS; DISSOCIATION; ELECTRON ATTACHMENT; ELECTRON-MOLECULE COLLISIONS; ELECTRONS; EQUILIBRIUM; EV RANGE; EXCITATION; EXCITED STATES; GEOMETRY; GROUND STATES; INELASTIC SCATTERING; MOLECULAR STRUCTURE; MOLECULES; MOMENTUM TRANSFER; R MATRIX; RESONANCE; SULFUR DIOXIDE; WAVE FUNCTIONS

Citation Formats

Gupta, Monika, and Baluja, K. L. Low-energy elastic and inelastic scattering of electrons from SO{sub 2} using the R-matrix method. United States: N. p., 2006. Web. doi:10.1103/PHYSREVA.73.0.
Gupta, Monika, & Baluja, K. L. Low-energy elastic and inelastic scattering of electrons from SO{sub 2} using the R-matrix method. United States. doi:10.1103/PHYSREVA.73.0.
Gupta, Monika, and Baluja, K. L. Sat . "Low-energy elastic and inelastic scattering of electrons from SO{sub 2} using the R-matrix method". United States. doi:10.1103/PHYSREVA.73.0.
@article{osti_20787101,
title = {Low-energy elastic and inelastic scattering of electrons from SO{sub 2} using the R-matrix method},
author = {Gupta, Monika and Baluja, K. L.},
abstractNote = {R-matrix method is used to calculate elastic differential, integral, and momentum transfer cross sections for electron-SO{sub 2} collision. The electron-impact excitation cross sections for first seven low-lying electronic excited states of SO{sub 2} molecule from the ground state of SO{sub 2} molecule have been calculated for the first time. Sixteen low-lying electronic states of SO{sub 2} molecule are included in the close coupling expansion of the wave function of the entire scattering system, which have vertical excitation energies up to 10.51 eV. Configuration-interaction (CI) wave functions are used to calculate these excitation energies. In our CI model, we keep the core 14 electrons frozen in doubly occupied molecular orbitals 1a{sub 1}, 2a{sub 1}, 3a{sub 1}, 4a{sub 1}, 1b{sub 1}, 1b{sub 2}, 2b{sub 2} and the remaining 18 electrons span the relevant active space: 5a{sub 1}, 6a{sub 1}, 7a{sub 1}, 8a{sub 1}, 9a{sub 1}, 2b{sub 1}, 3b{sub 1}, 3b{sub 2}, 4b{sub 2}, 5b{sub 2}, 6b{sub 2}, and 1a{sub 2}. Our calculated dipole moment of the ground state of SO{sub 2} at its equilibrium geometry is 0.79 a.u., which is in reasonable agreement with the corresponding experimental value 0.64 a.u. Our calculations detect one bound SO{sub 2}{sup -} state ({sup 2}B{sub 1}) at the equilibrium geometry of SO{sub 2} molecule. Both shape as well as core-excited shape resonances have been identified in the present work and are correlated with the experimental results on dissociative electron attachment study. A detailed analysis of resonances is provided. Cross sections are reported for the electron impact energy range 0-15 eV. All cross section calculations are performed in the fixed-nuclei approximation at the experimental equilibrium geometry of the ground state of SO{sub 2} molecule. We have also investigated dependence of resonances on the geometry of SO{sub 2} molecule to probe the possible pathways for dissociation of resulting negative ion upon electron attachment. We have excellent agreement of differential, elastic integral, and momentum transfer cross sections calculated in the 16-state R-matrix approximation with the available experimental results for electron-impact energy range 0-15 eV. Our resonant peaks correlate well with the peaks observed in the study of dissociative electron attachment (DEA) of electron with SO{sub 2} molecule.},
doi = {10.1103/PHYSREVA.73.0},
journal = {Physical Review. A},
number = 4,
volume = 73,
place = {United States},
year = {Sat Apr 15 00:00:00 EDT 2006},
month = {Sat Apr 15 00:00:00 EDT 2006}
}
  • The R-matrix method for electron-molecule scattering developed by one of us (B.I.S.) is applied to the elastic scattering of electrons from F/sub 2/ in the static-exchange approximation. Calculations are presented using both F/sub 2/ and F/sub 2//sup -/ core orbitals to construct the electron-molecule interaction potential. The total and differential elastic scattering cross sections are quite different for the two molecular fields and can be interpreted in terms of the presence or absence of an F/sub 2//sup -/ bound negative ion at the equilibrium internuclear separation in F/sub 2/. Since there is little experimental data on F/sub 2//sup -/ ormore » e + F/sub 2/ collisions, the calculations coupled with some detailed electron-beam experiments would be of great value in furthering our understanding of the chemistry of F/sub 2//sup -/. (AIP)« less
  • The R-matrix formulation of electron-molecule collision theory is applied to low-energy e-N/sub 2/ scattering in the static-exchange approximation. Particular attention is given to the determination of basis sets for such L/sup 2/-variational calculations, and a study of important basis-set characteristics in the context of this collision problem is presented. Results for elastic e-N/sub 2/ collisions for scattering energies in the range from about 0.01 to 13.0 eV are reported. The importance of including long-range interactions is briefly discussed.
  • We report on the calculated elastic differential, elastic integral, momentum transfer, and excitation cross sections for the low-energy electron-NH{sub 3} scattering using the R-matrix method. Elastic differential and momentum transfer cross sections are obtained by summing over rotationally elastic and rotationally inelastic cross sections for rotor states up to J=4. The excitation cross sections of the first four low-lying electronically excited states from the ground state of NH{sub 3}, at its equilibrium geometry, are presented. These excited states have symmetries a {sup 3}A{sub 1}, A {sup 1}A{sub 1}, b {sup 3}E, and B {sup 1}E. The set of self-consistent-field molecularmore » orbitals is obtained by optimizing these on the first excited state {sup 3}A{sub 1}. Configuration-interaction (CI) wave functions are used to represent the target states. In our CI model, we kept the core two electrons frozen in doubly occupied molecular orbital 1a{sub 1}, and the remaining eight electrons moved freely among the five molecular orbitals 2a{sub 1}, 3a{sub 1}, 1e, 4a{sub 1}, 2e. With this CI model, we obtain good agreement for the vertical spectrum of excited states with the experimental values. The Born approximation is employed to account for higher partial waves excluded in the R-matrix method to evaluate elastic cross sections. Cross sections are reported for the electron-impact energy range 0.025-20 eV.« less
  • A 15-state [ital R]-matrix calculation has been carried out at 685 energies ranging from 1--17 eV to depict the resonant profiles for the elastic differential cross sections and the angular distribution of the spin asymmetry [ital A][sub 1[ital s]-1[ital s]]([theta],[ital k][sup 2]) in the elastic scattering of spin-polarized electrons by spin-polarized hydrogen atoms at angles of 30[degree], 55[degree], 70[degree], and 90[degree]. The calculations are compared with experiments.
  • Using a crossed electron beam--molecular beam scattering geometry and the relative-flow technique, ratios of elastic differential cross sections of SO/sub 2/ to those of He have been measured at electron impact energies of 12, 20, 50, 100, 150, and 200 eV. At each energy, an angular range of 15/sup 0/ to 150/sup 0/ has been covered. These ratios have been multiplied by previously known He elastic differential cross sections to obtain elastic differential cross sections for SO/sub 2/. From a knowledge of differential cross sections, integral and momentum transfer cross sections have been determined. Using the two-potential theory of e-moleculemore » scattering, calculations were also performed and compared with the measurements.« less