Eur. Phys. J. D (2022) 76: 49
https://doi.org/10.1140/epjd/s10053-022-00378-7

Regular Article – Atomic and Molecular Collisions

K-shell ionization of 25–100 keV N^q+ (q = 3, 5) ions impinging on Al and Cu surfaces

¹ Institute of Modern Physics, Chinese Academy of Sciences, 730000, Lanzhou, China
² School of Nuclear Science and Technology, University of South China, 421001, Hengyang, China
³ School of Nuclear Science and Technology, Lanzhou University, 730000, Lanzhou, China
⁴ School of Nuclear Science and Technology, University of Chinese Academy of Sciences, 100049, Beijing, China

^b songzhy@impcas.ac.cn

Received: 16 January 2022
Accepted: 1 March 2022
Published online: 15 March 2022

Abstract

In this paper, K-shell X-ray spectra of nitrogen are measured by the interaction of N^q+ (q = 3, 5) ions with Al and Cu surfaces in the impact energy range of 25–100 keV. K-shell X-ray yields per incident ion and then ionization cross sections are deduced from the measured K-X-ray spectra. It is found that both the yields and cross sections increase quickly with increasing impact energy, but have no apparent dependence on the target material and the charge state of the incident ion. The experimental results reveal that the incident N^q+ (q = 3, 5) ions have been neutralized and achieved a charge-state equilibration before the K-shell electron is ionized. The experimental ionization cross sections are compared with those from the plane wave Born approximation (PWBA) and the classical binary encounter approximation (BEA) theory. The BEA calculations are better consistent with the experimental data than the PWBA. It means that the K-shell ionization of the incident N^q+ (q = 3, 5) ions is due to the direct Coulomb excitation processes that occurred below the target surface.