Relativistic eigenchannelR-matrix studies of the strong intrashell electron correlations in highly chargedAr13+ions

Abstract

Highly charged ion systems play an important role in simulation and diagnostics of astrophysical and fusion plasmas. Due to dominant strong Coulomb interactions from the nuclear charge, electron correlations are generally thought to be less prominent than relativistic effects and other effects in HCIs. In this paper, we demonstrate the importance of strong intrashell electron correlations from the quasidegeneracy of 2s, 2p orbitals in highly charged B-like Ar 13+ ions. Such strong intrashell electron interactions manifest as an atomic system with many channel interactions, which will ultimately form a much more complex atomic spectrum than the neutral B atom in the isoelectronic sequence. As a typical example, the relativistic eigenchannel R-matrix method (R-R-eigen code) was successfully applied to investigate the complex spectrum of Ar 13+ ions with J π = 1.5 + symmetry in discrete and autoionization regions. Calculated results obviously show interesting behaviors of strong intrashell electron correlations in HCIs. Additionally, it is also beneficial to understand discrepancies in the low-energy electron-ion recombination spectra of Be-like Ar 14+ ions between experimental observations at the main cooler-storage ring of the Heavy Ion Research Facility in Lanzhou and distorted wave calculation.

Theoretical study of electron-impact broadening for highly charged Ar XV ion lines

“…These resonant structures can be effectively calculated using multichannel quantum defect theory. [26] As shown in Eq. ( 4), this paper discusses that electron collision broadening is a convolution result.…”

“…Highly ionized excited states have strong intrashell corrections, resulting in dense resonant structures. [26] Figure 2 shows that the collision excitation strengths Ω αβ and the collision strength for electron-impact broadening Γ αβ have a large number of resonance structures under the Ar XV threshold, while the results of the distorted wave calculation with identical target states 053101-5 using the Flexible Atomic Code (FAC) program [42] do not. These resonant structures can be effectively calculated using multichannel quantum defect theory.…”

“…Such threshold quasidegeneracy would produce dense resonance structures in collision processes. [26] An Ar XV ion can be regarded as a highly ionized ion. [26] Fernández-Menchero [27] used the frame transformation R-matrix method to calculate only the electron collision strengths of Be-like ions, and the relativistic effect was not strictly considered.…”

“…[26] An Ar XV ion can be regarded as a highly ionized ion. [26] Fernández-Menchero [27] used the frame transformation R-matrix method to calculate only the electron collision strengths of Be-like ions, and the relativistic effect was not strictly considered. Additionally, previous investigations on Ar XV line broadening only used the semiclassical perturbation method [28] and the nonrelativistic distorted wave approach, [29] in which the contribution of resonance structures to electron-impact broadening was not included.…”

Spectroscopy and scattering matrices with nitrogen atom: Rydberg states and optical oscillator strengths

“…Fortunately, there is a correlative relationship between the atomic energy levels and corresponding electronion collision processes in terms of the analytical continuation property of the short-range scattering matrices. [16][17][18] Depending on this property, the eigenchannel based on a relativistic R-matrix (R-R-Eigen) [19][20][21] could provide the required atomic data mentioned above with adequate precision. In the scenario of an R-R-Eigen, a half-collision model where it could be regarded as an ion in low-lying excited states combined with an incident electron in the bound orbital or the continuum orbital composes the atomic system.…”