Polarization degrees of 3p ²P_3/2–3s ²S_1/2transition in O⁵⁺(1s²3p) produced in collisions of O⁶⁺with He and H₂

Abstract

Electron capture processes in collisions of O6+ with ground state He and H2 are investigated using the two-centre atomic orbital close-coupling method. Total and state-selective one-electron capture cross sections are obtained for collision energies between 0.5 and 300 keV/u. The comparison with the available experimental state-selective capture data in the overlapping energy range (0.5–100 keV/u for O6++He and 0.5–8 keV/u for O6++H2) shows a good overall agreement. The polarization degrees of 3p 2P3/2–3s 2S1/2 radiation from O5+(3p 2P3/2) produced in O6++He and O6++H2 collisions are calculated from the magnetic substate-selective cross sections with inclusion of cascade contributions from higher n = 4 and n = 5 states. Good agreement is obtained with the experimental data available in the energy range 3–8 keV/u. Below ∼10 keV/u, the polarization degrees of O5+(3p 2P3/2) in both collision systems exhibit an oscillatory structure and above this energy they steadily increase with the increase of collision energy, reaching the values of about 0.37 at 300 keV/u. The energy behaviour of the polarization degree of O5+(3p 2P3/2) in the O6++He collision system is determined almost exclusively by the direct electron capture to 3p0 and 3p1 states of O5+, while in the case of the O6++H2 collision system in the energy region below ∼40 keV/u it is strongly affected by the cascade contributions from the 4l states, which are the dominant capture states in this system.

State-selective Charge Exchange in 19.5–100 keV amu−1 O6+ Collision with He and H2

“…Previous studies show that TC-AOCC calculations are in good agreement with measurements below 10 keV amu −1 (Zhao et al 2010). In the current study, the l-resolved relative cross sections were only extracted for the n = 3 channel for He at a collision energy of 19.5 keV amu −1 and for the n = 2 channel at a collision energy of 37.5-100 keV amu −1 .…”

“…For astrophysical EUV and X-ray spectrum modeling, the principal quantum number n and orbital angular momentum number l resolved state-selective CX cross sections are necessary, since they determine the following X-ray and EUV line emissions and intensity ratios. Mostly in modeling, the state-selective data are obtained with theoretical methods like classical trajectory Monte Carlo (CTMC; Olson & Salop 1976, 1977Olson 1981), multichannel Landau-Zener (Cumbee et al 2016;Lyons et al 2017), and two-center atomic orbital close coupling (TC-AOCC; Fritsch & Lin 1984;Zhao et al 2010). For example, using CX data calculated with CTMC, several studies (Kharchenko et al 2008;Hui et al 2010;Schultz et al 2017;Houston et al 2018Houston et al , 2020 have made attempts to reproduce the X-ray emission spectrum and the flux of Jupiter's polar caps (Liu & Schultz 1999).…”

Measurement and calculation of absolute single- and double-charge-exchange cross sections forO6+ions at 1.17 and 2.33 keV/u impacting He andH2

“…In addition to results of the present CTMC theoretical approach, state-selective cross sections have been calculated by extension of atomic-orbital expansion with close coupling to a two-electron system [50], in a combined ab initio approach (for the potential energy curves and couplings) with a semiclassical collision calculation [51], the traveling molecular-orbital method [52], a semiclassical molecular-orbital approximation [53], and the two-center atomic-orbital close-coupling method [54]. Spectroscopic measurements of state-selective cross section for charge transfer have been carried out for several ions, including O 6+ colliding with He and H 2 in an energy range containing the present impact energies [38].…”

Charge transfer in collisions of Beq+(q=2-4) and Bq+(q=3-5) ions with H

“…The electron capture processes of multiply charged impurity ions in magnetic fusion plasma with the neutral hydrogen species are also important in the studies of impurity transport in the edge and divertor plasma regions [2]. In the past three years, as one of the participants in the IAEA Coordinated Research Program on data for light ions, we have studied the collision processes between some basic edge/divertor plasma constituents (H + , H, He, H 2 ) and the light element atomic and molecular plasma impurities including Li, Be, B, C, N, O ions [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] by using the quantal molecular orbital close-coupling (QMOCC) and the two-center atomic orbital close-coupling (TC-AOCC) methods over a large energy region.…”

“…Beryllium is the adopted first wall material for the International Thermonuclear Experimental Reactor (ITER) [4]. The charge transfer cross sections for Be 4+ +H and B 5+ +H collisions are calculated by using the TC-AOCC method and sets [6,7].…”