Relative Intensities of the 3d-2p Lines Emitted by Ar13+Ions after Impact Excitation by an Electron Beam

Abstract

The intensity ratio R of the dipole-allowed lines 3d D3/2,5/2 → 2p P3/2 and 3d D3/2 → 2p P1/2 emitted from highly charged boron-like Ar ion collisionally excited by a monoenergetic electron beam has been theoretically studied versus electron densities from 10 to 5× 10 cm−3. The calculations were performed at different angles θ of observation with respect to the electron beam direction and various incident-electron energies e i from 0.65 to 3 keV. By taking into account all important transitions among 290 magnetic sublevels of the 2s2p, 2s2p, 2p, 2s3l, 2s2p3l, 2p3l (l = 0−2) configurations, a collisional-radiative model has been used for determining the populations of the upper magnetic sublevels of the lines. All required atomic data were computed with the Flexible Atomic Code. We find that the effect of anisotropy in the photon emission, due to the directionality of the incident electron beam, can lead to very significant differences between R(0◦) and R(90◦). Our results also indicate that the contribution from the D3/2 → P 3/2 line which blends with the D5/2 → P 3/2 line enhances the effect of anisotropy.