The adoption of Heavy Ion PIXE for elemental quantification remains limited by the lack of fundamental atomic parameters needed for the calculation of X-ray production cross section data. Widely adapted theoretical models used for approximating ionisation cross sections, as well as other atomic physical parameters such as X-ray fluorescence yields, are calculated based on single-hole vacancy production post ion-atom impact. This renders the use of conventional ‘protonic’ models invalid for heavy ion-atom collisions. The degree to which Multiple Ionisation (MI) manifests in different heavy ion-atom collision symmetries significantly modifies atomic physical parameters. This is due to the significant number of introduced spectator vacancies in higher subshells, especially where near-symmetry is approached and MI is more pronounced. Knowledge of the mean number of vacancies in upper subshells is thus important for modifying atomic parameters that are needed for the translation of ionisation to X-ray production cross sections. In the present study, MI effects for Sn L-shell X-rays were studied using characteristic X-ray energy shifts measured using a standard PIXE spectrometer induced by Si, Cu and I projectile ions with incident energies up to 0.75 MeV/u. MI satellite distributions were studied using a Wavelength dispersive X-ray spectrometer (WDS) for high resolution PIXE, induced by C and Si projectile ions with incident ion energies up to 1.25 MeV/u. The mean number of subshell vacancies in the M- and N- shell for energy shifted Sn Lα X-ray lines were determined using both standard and high resolution PIXE spectrometers.

中文翻译：

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重离子撞击倍电离 Sn 原子中的实验亚壳空位


由于缺乏计算 X 射线产生横截面数据所需的基本原子参数，采用重离子 PIXE 进行元素定量仍然受到限制。用于近似电离截面以及其他原子物理参数（如 X 射线荧光产率）的广泛采用的理论模型是根据离子原子撞击后单孔空位产生计算的。这使得使用传统的 “protonic” 模型对于重离子-原子碰撞无效。多重电离 （MI） 在不同重离子-原子碰撞对称性中的表现程度显着改变了原子物理参数。这是由于在更高的子壳层中引入了大量观众空缺，尤其是在接近接近对称且 MI 更明显的情况下。因此，了解上部亚壳层中空位的平均数量对于修改将电离转化为 X 射线产生横截面所需的原子参数非常重要。在本研究中，使用入射能量高达 0.75 MeV/u 的 Si、Cu 和 I 弹射离子诱导的标准 PIXE 光谱仪测量的标准 X 射线能量转移来研究 Sn L 壳 X 射线的 MI 效应。使用波长色散 X 射线光谱仪 （WDS） 研究高分辨率 PIXE，由入射离子能量高达 1.25 MeV/u 的 C 和 Si 弹射离子诱导。使用标准和高分辨率 PIXE 光谱仪确定了能量转移 Sn Lα X 射线线的 M 壳层和 N 壳层中亚壳空位的平均数量。