Electron impact ionization of Kr XI–Kr XIX ions

Triple differential cross sections (TDCSs) for (e, 2e) processes on the valence electrons of H-, Li-, Na- and K-like positive ions are calculated for asymmetric coplanar geometries and intermediate incident energies. Although the proper boundary conditions are not respected, both the long-range Coulomb interaction in the initial and final channels, and the short-range effects, are taken into account in the Coulomb Born approximation through the use of two effective charges. The latter are obtained within the framework of the frozen-core Hartree–Fock approximation which is also used for describing the bound state wavefunctions. An approximate scaling law for the TDCSs is predicted for the ionization of sequences of isoelectronic ions, provided the incident and ejected energies are properly scaled. The calculations illustrate that the scaling is generally well verified, in particular for increasing ionicity within a sequence. Moreover, as one moves from the H- to K-like sequences, more TDCS structure is observed. Two main peaks are always situated close to the direction of the momentum transfer and opposite direction, although with strong shifts. Contrary to what is observed for the ionization of outer-shells electrons in neutral atoms, the dominant peak of all cross sections is in the opposite direction to the momentum transfer, a signature of strong elastic scattering from the nucleus.

Section: Introductionmentioning

confidence: 99%

Scaling law for (e, 2e) cross sections for isoelectronic hydrogen- and alkali-like ions

Ancarani¹,

Hervieux²

2003

“…In the higher collision energy region above 8 eV, a much better agreement was achieved between the measured and theoretically calculated DR rate coefficients. However, a large discrepancy, which is beyond the experimental uncertainty, appears in [35][36][37][38] eV where strong resonances have been observed. The reason is probably due to the extra resonant channels of 2p 4 [ 1 D 2 ]6l and 2s2p 3 [ 3 D 1 ]9l, and the former corresponds to the TR process associated with a free electron captured into n = 6 Rydberg state along with the excitations of two 2s electrons into 2p shell.…”

Section: Dr Rate Coefficientsmentioning

confidence: 95%

“…Therefore, the comprehensive knowledge of the atomic data, including the excitation energies, ionization cross sections and recombination rates, for all the charge states of krypton is required to model and diagnose the plasma. Many theoretical calculations have been performed to calculate the cross sections of ionization, excitation and recombination processes of krypton ions [8,[35][36][37][38]. Many experiments have been carried out and various atomic data for krypton ions have been obtained, such as the spectroscopic measurements of H-like to O-like krypton ions for KLL DR resonances strength in the electron beam ion trap [39,40], and storage rings DR measurements for Kr 25+ and Kr 33+ [41][42][43]…”

Section: Introductionmentioning

confidence: 99%

Dielectronic recombination rate coefficients of carbon-like Kr³⁰⁺

Wang

Huang

et al. 2023

Dielectronic recombination (DR) rate coeﬃcients for carbon-like Kr30+ have been measured over the collision energy of 0-60 eV using the heavy-ion storage ring CSRe at the Institute of Modern Physics in Lanzhou, China. The present DR spectrum covers the resonances associated with the 2s^22p^2[3P0] → 2s^22p^2[3P1,2], 2s2p^3 and 2p^4 (∆N = 0) core excitations. The corresponding DR resonance energies and strengths have been calculated by using the ﬂexible atomic code (FAC) to understand the measured results. An overall agreement has been obtained between the experiment and theory, except for the data at the collision energies below 7 eV and in 35-38 eV, where the electronic correlation eﬀect is strong. In particular, the resonances from the trielectronic recombination due to 2s^22p^2 + e- → 2p^4[1D2]6l have been identiﬁed with the help of the FAC calculation. Temperature-dependent plasma recombination rate coefficients were derived from the measured DR rate coefficients for the temperature range 10^3 − 10^7 K and compared with our FAC calculations as well as the previous AUTOSTRUCTURE calculations by Zatsarinny et al: (2004 Astronomy & Astrophysics 417 1173-1181. The FAC and AUTOSTRUCTURE calculations are in good agreement with the presently derived plasma rate coefficients. The present work provides the benchmark data for astrophysical and laboratory plasma modelling.

“…In the case of ionization excitation of atomic species [2], such as helium, the photon and electron coincidence detection techniques are necessary to measure the corresponding cross sections, while for dissociative diatomic species, such as diatomic hydrogen or lithium, the spectroscopic detection is not necessary, if one can detect the ejected electron in coincidence with the emerging proton. In recent years, intense experimental and theoretical research of both simple [2][3][4][5][6] and multiple [7][8][9][10][11][12] ionization of atomic and molecular systems by electron impact has been carried out using the coincidence detection of the emerging particles. In the case of dissociative ionization, the coincidence detection of the two electrons and the emerging ions is now possible [13,14].…”

Section: Introductionmentioning

confidence: 99%

Ionization excitation of diatomic systems having two active electrons by fast electron impact: a probe to electron correlation

Serov

Joulakian²,

Derbov

et al. 2005

(e, 2e) ionization excitation of diatomic hydrogen to the first dissociative state of H+2 by fast electrons is studied theoretically using the prolate spheroidal two-centre continuum numerical solutions to construct the partial-wave description of the slow ejected electron in a variety of situations. Our results confirm the fundamental role of the initial bound state ‘left–right’ correlation and show the breakdown of dynamical behaviours observed in the case of simple (e, 2e) ionization. Actually realizable complete experiments detecting the scattered and ejected electrons in coincidence with the bare detached nucleus are expected to verify our theoretical predictions.