Electron scattering from molecules: elastic processes and rotational excitations

Abstract

Quantum calculations are carried out for the scattering of electrons from sulphur dioxide molecules in the energy range from about 1.0 eV up to 30 eV. Integral and differential cross sections are obtained for the elastic process and for the excitation processes of the target asymmetric rotor into various final rotational levels. Comparison with experimental data, both of the momentum transfer cross sections and the angular distributions, indicates rather good agreement between measured and computed values over the whole range of the examined energies, while the integral elastic cross sections (rotationally summed) show disagreement at low energy with the experimental estimates. Born corrections to the calculations are also shown to provide the correct behaviour of the forward scattering angular distributions and a reliable guide to experimental extrapolation procedures.

Theoretical total cross sections fore-SO2scattering over a wide energy range (0.1−2000 eV) revealing a 3.4-eV shape resonance

“…From the present CI calculations the ground-state energy for SO 2 is − 547.20 hartree which is in excellent agreement with − 547.28 hartree reported by Gupta and Baluja [14] and − 547.28 hartree reported by Machado et al [17], but higher than the theoretical value of − 567.232 hartree reported by Gianturco et al [15] by 20 hartree. The excitation energy of the first excited state is calculated to be 3.794 eV, which is in excellent agreement with the theoretical value of 3.75 eV predicted by Gupta and Baluja [14] and is close to the experimental value of 3.4 eV reported by Flicker et al [29] and 3.5 eV reported by Vuskovic and Trajmar [30].…”

“…The excitation energy of the first excited state is calculated to be 3.794 eV, which is in excellent agreement with the theoretical value of 3.75 eV predicted by Gupta and Baluja [14] and is close to the experimental value of 3.4 eV reported by Flicker et al [29] and 3.5 eV reported by Vuskovic and Trajmar [30]. The rotational constant obtained in the present calculation is 2.025 cm −1 and is in excellent agreement with the experimental value of 2.02 cm −1 from Computational Chemistry Comparison and Benchmark Database (CCCBDB) [27] but, again, lower than the theoretical value of 3.0 cm −1 reported by Gianturco et al [15]. The present dipole moment at the equilibrium geometry is 2.1 D, which is comparable with the experimental value of 1.63 D [6] and slightly higher than the theoretical value of 1.92 D predicted by Natalense et al [16] and lower than the 2.4 D reported by Gupta and Baluja [14].…”

“…Very recently Machado et al [17] reported the results of a joint theoretical (1-1000 eV) and experimental (100-1000 eV) study to determine total cross sections for e-SO 2 scattering. It should be noted that these earlier theoretical works [14][15][16][17] were not able to predict the shape resonance reported in Refs. [12,13].…”

“…Gupta and Baluja [14] have calculated total elastic cross sections using the R-matrix method for impact energies 0-15 eV. Gianturco et al [15] performed ab initio calculations for the energy range 0-30 eV and Natalense et al [16] employed the Schwinger multichannel method and computed rotationally summed inelastic, differential and integral, and momentum transfer cross sections for electron scattering for impact energies from 3 to 30 eV. Very recently Machado et al [17] reported the results of a joint theoretical (1-1000 eV) and experimental (100-1000 eV) study to determine total cross sections for e-SO 2 scattering.…”

“…Thus reviewing previous work on e-SO 2 scattering it is notable that there are more experimental data [6][7][8][9][10][11]13,17] than theoretical investigations [11,12,14,15,17]. The other notable fact is that although e-SO 2 has been studied over a wide range of impact energies, all of the previous groups have carried out work over a limited range of impact energies.…”