Charge state effect on K-shell ionization of aluminum by 600–3400 keV xenonq+ (12 < q < 29) ion collisions
Charge state effect on K-shell ionization of aluminum by 600–3400 keV xenonq+ (12 < q < 29) ion collisions
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DOI：
10.1140/epjd/e2011-20173-5
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发表时间：
2011-08
期刊：
影响因子：
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通讯作者：
Z. Song;Zhongshi Yang;G. Xiao;Qiu-mei Xu;J. Chen;Bian Yang;Z. Yang
中科院分区：
文献类型：
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作者：
Z. Song;Zhongshi Yang;G. Xiao;Qiu-mei Xu;J. Chen;Bian Yang;Z. Yang
Al 的 K 壳 X 射线光谱是通过 600–3400 keV Xeq+(q= 12–29) 离子与 Al 表面的相互作用来测量的。推导出每个入射离子的X射线产额，并从实验产额数据获得K壳层电离截面。在相同的入射能量下，Xeq+(q<26)离子激发的Al的K壳层电离截面具有相同的数量级，而对于q=26和29Xe离子碰撞，它们分别大约2倍和10倍。考虑到目标原子的结合能修饰和反冲效应，二元相遇近似（BEA）理论与q<26 Xe离子碰撞的实验数据一致，但低估了q= 26和29 Xe离子激发的碰撞数据。这表明 Xeq+(q<26) 离子引起的靶标 K 壳层电离主要是由于直接库仑激发。然而，对于 q= 26 和 29 Xe 离子碰撞，通过离子原子准分子中形成的 3dπ,δ-3dσ 分子轨道的旋转耦合，弹丸的 3d 空位转移到目标的 1 轨道，可能会对电离的增强产生相当大的贡献。除了众所周知的俄歇跃迁和X射线跃迁之外，我们的实验证明分子轨道跃迁（“侧馈”）机制也是表面下方形成的空心原子去激发的重要通道。
K-shell X-ray spectra of Al were measured by the interaction of 600–3400 keV Xeq+(q= 12–29) ions with Al surface. The X-ray yields per incident ion were deduced and theK-shell ionization cross-sections were obtained from the experimental yield data. With the same incident energy, theK-shell ionization cross-sections of Al excited by Xeq+(q<26) ions were of the same order of magnitude, while forq= 26 and 29 Xe ion collisions, they were, respectively, about two and ten times larger. Taking into account the binding-energy-modification and the recoil effect of target atoms, the binary encounter approximation (BEA) theory was consistent with the experimental data forq<26 Xe ion collisions, but it underestimated those excited byq= 26 and 29 Xe ions. This indicates that theK-shell ionization of target induced by Xeq+(q<26) ions was mainly due to the direct Coulomb excitation. However forq= 26 and 29 Xe ions collisions, the transfer of 3dvacancies of projectile to the 1sorbital of target via rotational coupling of the 3dπ,δ-3dσmolecular orbitals, which were formed in the ion-atom quasi-molecule, may cause a considerable contribution to the enhancement of ionization. In addition to the well known Auger and X-ray transition, our experiments proved that the molecular orbital transition (“side-feeding”) mechanism is also a significant channel for de-excitation of hollow atoms formed below the surface.