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.

中文翻译：

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Ag 与 15 keV 电子碰撞时的 L3-亚壳排列。

使用粒子诱导 X 射线发射 (PIXE) 技术在元素分析中研究碰撞过程中原子的排列非常重要。对准的测量还可以为开发电离过程中的理论模型提供有效的测试基础。典型的 L X 射线光谱是通过 15 keV 电子撞击在 0° 到 25° 的发射角下测量 Ag 薄靶的。强度比 Lα/Lβ1、Lβ2/Lβ1 和 Lγ/Lβ1 的角度依赖性被研究为二阶勒让德多项式 P2(cosθ) 的函数。本研究发现Lβ2线在空间上呈现各向异性发射，而Lα、Lβ1和Lγ1线的发射则是各向同性的。通过 Coster-Kronig (CK) 跃迁对 X 射线发射空间分布的影响来解释结果。Lβ2 线的各向异性参数 β 是通过实验获得的，因此 L3 子壳的对齐度 A20 是通过考虑 CK 转变来确定的。即，排列确实存在于 L3 亚壳层中，用于通过电子碰撞进行原子电离。测量结果为电子撞击过程中原子电离排列的存在提供了证据。