Subjects: Physics >> Nuclear Physics Subjects: Physics >> Atomic and Molecular Physics submitted time 2024-02-22
Abstract： The state-selective single-electron capture process in the collision of N+ ions with He at an energy of 0.64 keV/u has been experimentally studied by the reaction microscopy with a two-fold coincident method, and the state-selective cross-sections and angular distributions of an electron captured into different quantum states of the projectile ions have been obtained. The experimental results show that: the ground state projectile N+(3P) captures a 1𝑠 electron from the He target mainly to the 2𝑝 shell, and the contribution to the higher shells can also be observed; the metastable N+(5S) captures a 1𝑠 electron from the He target mainly to the 2𝑠 shell, with almost no contribution to higher shells. The experimental results are interpreted qualitatively using the potential energy curves of the NHe+ quasimolecular ion, but the reaction window predictions of the molecular Coulomb over-barrier model differ significantly from the experiments. During the capture of the target electron into the 2𝑠 orbital by the metastable projectile N+(5S), a clear oscillatory structure appears in the angular differential cross-section, which is likely to result from Demkov-type transitions.
Subjects: Physics >> Atomic and Molecular Physics submitted time 2023-12-03
Abstract： Experimental and theoretical research on X-ray emissions following charge exchange between slow highly charged ions and atomic Hydrogen supply vital atomic data in the study of diagnosing and simulating plasmas in non-equilibrium astrophysical environment. In the present paper, employing the semiclassical multi-channel Landau-Zener (MCLZ) method, we calculated the total cross-section of bare and hydrogenic C, N, O ions charge exchange with hydrogen atoms, and compared it with previously reported experimental results. In C5 + H collision, theoretically calculated cross-sections have large differences with experimental cross-sections. We also compared state-selective cross-sections calculated by classical MCLZ and quantum-mechanical molecular orbital close-coupling(QMOCC) methods in the solar wind ion velocity (or energy) range. For capture to n = 3 shell, MCLZ calculated state-selective cross-section increase with collision energy increasing; For capture to n = 4 shell, MCLZ calculated state-selective cross-section decrease with collision energy increasing; It is lower than two magnitudes as QMOCC method calculated cross-section. Finally, using the Kronos program package developed in the astrophysical field, we calculated the X-ray emission spectrum, line ratio, and hardness ratio of charge exchange of 1000 eV/u O8 by means of recommended cross-section by Janev, and contrast with the MCLZ method calculated results. We consider that the MCLZ calculation has a large uncertainty, which could affect the accuracy of the astrophysical environment simulation. It is required for developing a more accurate full quantum theory.
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