L₃-subshell alignment of Ag in collision with 15 keV electrons

Article type: Research Article

Authors: Hu, Pengfei | Wang, Xing^{; *}

Affiliations: School of Science, Xi’an Jiaotong University, Xi’an, China

Correspondence: [*] Corresponding author: Xing Wang, School of Science, Xi’an Jiaotong University, 710049 Xi’an, China. E-mail: wangxingcn@xjtu.edu.cn.

Abstract: It is of great importance to study the alignment of atoms in collision process in elementary analysis with a Particle Induced X-ray Emission (PIXE) technique. The measurement of alignment can also offer an effective testing ground for developing theory models in ionization process. The typical L X-ray spectra are measured for Ag thin target by 15 keV electron impact at emission angles from 0° to 25°. Angular dependence of intensity ratios Lα/Lβ1, Lβ2/Lβ1 and Lγ/Lβ1 are investigated as a function of the second-order Legendre polynomial P2(cosθ). This study found that Lβ2 line exhibits anisotropic emission spatially, while the emission of Lα, Lβ1 and Lγ1 lines is isotropic. The results are interpreted by the influence of the Coster-Kronig (CK) transitions on the spatial distribution of X-ray emission. The anisotropy parameter β for Lβ2 lines is obtained experimentally and consequently the alignment degree A20 for L3 subshell is determined by taking CK transition into account. Namely, the alignment does exist in L3-subshell for atomic ionization by electron impact. The measurements offer an evidence to the existence of alignment for atomic ionization in electron-impact process.

Keywords: X-ray, angular distribution, particle induced X-ray emission (PIXE), electron impact, alignment of atoms

DOI: 10.3233/XST-200701

Journal: Journal of X-Ray Science and Technology, vol. 28, no. 5, pp. 1017-1023, 2020