Inelastic electron scattering from excited barium atoms


Background. Progress in the field of physics of electron-atom collisions is dependent on two main factors: a) the availability of new studies of individual atomic systems; b) the clarify, systematize and generalize of results, obtained in previous studies. In the last two decade we, together with co-authors, investigate in detail the elastic and inelastic electron scattering on neutral atomic systems Mg, Ba, Sr, Ca, Si, F, Al, and B. The purpose of this paper is to systematize and summarize the results of studies of Ba atom, and is to continue the investigation of the scattering integral cross sections of electrons on the excited barium atom, begun in our previous work.
Methods. The atomic structure for Ba, as well as the excitation cross sections for e−Ba scattering processes were obtained by the R-matrix with pseudostates method. The multiconfiguration Hartree-Fock method with orthogonal orbital sets was employed for an accurate representation of the targets wave functions. The close coupling expansions include 38 term: 16 spectroscopic states of neutral barium and 22 pseudostates. The scattering calculations was then carried out in the same way as in standard R-matrix calculations.
Results. The integral cross sections for the scattering of low-energy electrons by a barium atom in the excited states 6s5d3D and 6s5d1D are calculated. The calculations were carried out in the R-matrix approximation with pseudostates. The collision strengths were calculated in the close coupling channels approximation with allowance for 38 terms. The latter include 16 physical states of the target and 22 pseudostates accumulated in the LS-coupling. The cross sections obtained in the R-matrix approximation exhibit a pronounced resonance structure. A comparison was made of the calculated ICS scattering e-Ba with the available experimental data. A good agreement between the theory and experiment was obtained.
Conclusions. For the e-Ba collisions were the scattering cross-sections calculated. All transitions from the excited 6s5d3D and 6s5d1D states of the Ba atom to the 15 lowest excited levels were considered. The energy dependences of the IСS on the type of spectral transition in the Ba atom were discussed

Keywords: Ba atom, pseudostates, electron scattering, channels close coupling, R-matrix method, scattering integral cross-sections