Investigation of the doubly excited autoionizing states in Helium-like ions

The recent advent of X-ray free electron lasers (XFELs) opens the possibility to trigger the formation of doubly excited autoionizing states (DEAS) in atoms and to investigate their role in the ionization process.  Accurate theoretical knowledge of where these states can be located in the energy spectrum of the targeted system and their precise lifetime decay will be a support to the future experiments on the laser-atom processes involving the DEAS.  In this work, we theoretically investigate the DEAS in the Helium-like O⁶⁺ and F⁷⁺ ions by using a B-spline based spectral approach [1,2] combined with the complex rotation method [3]. We show how our method has successfully detected new high lying DEAS in the O⁶⁺ion [4] and the F⁷⁺ ion. The method generates precise values of the energy positions and lifetime decays of the DEAS. It also allows the identification of the states that share similar angular correlation pattern. The theoretical results generated in this work will be of great interest to the future experiments on the O⁶⁺ and F⁷⁺ with XFELs.

  

[1] S. Barmaki, M.-A. Albert, S. Laulan, Chem. Phys. 517, 24 (2019)  

[2] S. Barmaki, M.-A. Albert, S. Laulan, J. Phys. B: At. Mol. Opt. Phys. 51, 105002 (2018)  

[3] M.- A. Albert, S. Laulan, S. Barmaki, Radiat. Phys. Chem. 166, 108453 (2020)  

[4] S. Barmaki, M.- A. Albert, S. Laulan, Phys. Scr. 95, 055403 (2020)