Theoretical photoionization spectra in the UV photon energy range for a Mg-like Al⁺ion

Abstract

In the present work, we report the photoionization cross sections of the Al+ ion calculated for the photon energy range 20–26 eV and 30–50 eV. We have expanded our previous calculation (2007 J. Phys. Soc. Japan 76 014302) with an optimized admixture of the initial ground state 3s21S and exited states 3s3p1,3P, 3s3d1,3D and 3s4s1,3S, and obtained significantly improved predictions for the main background and autoionizing resonance structures of the reported experimental spectra. The absolute measurements of the photoionization cross sections of the Al+ ion in these energy ranges have been performed by West et al (2001 Phys. Rev. A 63 052719), and they reported that the prominent peaks around 21 eV were attributed to the effects of the significant influence of the small fraction of the fourth-order radiation with energies around 84 eV from the synchrotron source. In our previous work, the main shape for these cross sections was calculated assuming an admixture of initial 3s21S and 3s3p3P states, only with a rough overall estimate for the experimental spectra in the photon energy range 20–26 eV, and without these peaks around 21 eV. The report of the experimental assignment attributes these peaks to the excitation of a 2p electron from the core. However, our present results with the new admixture reveal similar peaks without considering the possibility of the core excitation.

L -shell photoionization of Mg-like S4+ in ground and metastable states: Experiment and theory

“…Previous work on S 4+ includes the theoretical calculation of oscillator strengths and photoionization cross sections along the magnesium sequence (including S 4+ ) [27] and the calculation of the valence absorption spectrum of S 4+ [28,29]. Doubly excited autoionization resonances for the S 4+ isoelectronic cases of Al + and Si 2+ [30] and photoionization spectra in the UV range for the Mg-like Al + ion [31] were also investigated theoretically. Experimental investigations of the 2p-subshell photoabsorption of the isoelectronic Al + and Si 2+ ions were carried out using the DLP technique [32,33] and for the Al + ion by the synchrotron photon-ion merged beam technique [34][35][36].…”

L-Shell Photoionization of Magnesium-like Ions with New Results for Cl5+

“…Photon-driven excitation and ionization along the magnesium isoelectronic sequence have long been of interest in experimental and theoretical investigations e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. This is not surprising, given the nature of magnesium-like systems with their simple closedsubshell ground state configuration 2p 6 3s 2 .…”

Theoretical photoionization spectra for Mg-isoelectronic Cl5+and Ar6+ions

“…Measurements of absolute photoionization spectra for Mg-isoelectronic Al + and Si 2+ ions have been carried out by West et al [12] and Sayyad et al [13]. On the other hand, the first calculation for photoionization spectra of a Mg atom was performed by Bates and Altick in 1973 [14], and the characteristics of Mg-isoelectronic series have attracted a great deal of interest theoretically [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30]. In particular, the Opacity Project (OP) team [31] have performed a number of remarkable theoretical works.…”

“…As a part of the work for Mg isoelectronic sequence, we extended the preceding work for the Mg-isoelectronic S 4+ ion [29] to Mg-isoelectronic Al + [28] and Si 2+ ions [30], and here report the cross sections for photoionization of the Mg-isoelectronic Cl 5+ and Ar 6+ ions for photon-energy ranges from the first 3s threshold to the 4s threshold, using the non-iterative variational R-matrix method [26]. Photoionization processes considered are as following,…”