Measurement and R-matrix calculation of superelastic electron-scattering cross-sections on the metastable (3s3p) <sup>3</sup>P<sub>0,2</sub>states in Mg

Abstract

In the present paper the results experimental and theoretical investigations of superelastic scattering on the metastablc 3s3p 3 P 0,2 states of Mg represented. The experiments have been carried out on conditions of crossed electron and atomic beams. In experiment the part of integral cross section for super-elastic scattering in the range of scattering angles from 0 to ~ 0.5 rad was measured. Energy dependence of these cross sections for super-elastic scattering from metastable 3 3 P 0,2 states of Mg atom was obtained in the near-threshold region for energies from 0.15 up to 3 eV. The relative accuracy of obtained cross sections is estimated to be ~ 8%, the energy scale calibration errors are less then 0.1 eV. The resonance structure at electron energy -0.45 eV was obtained. We used R-matrix method with pseudo-states in 35-state intermediate-coupling approximation for the calculation of electron-impact excitation cross sections in neutral Mg. The close-­coupling expansion includes the 21 physical target slates and 14 pseudo-states in the LSJ coupling scheme. The good agreement in the energy dependence of experimental and theoretical cross section at energies greater than 0.4 eV, but larger difference is observed in the near-threshold region was obtained. The origin of this difference is not clear, and further both theoretical and experimental investigations are desirable in this respect.