Ionization potentials of the lanthanides and actinides – towards atomic spectroscopy of super-heavy elements
Ionization potentials of the lanthanides and actinides – towards atomic spectroscopy of super-heavy elements
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DOI：
10.1007/s10751-014-1041-8
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发表时间：
2014-02
影响因子：
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通讯作者：
K. Wendt;T. Gottwald;C. Mattolat;S. Raeder
中科院分区：
文献类型：
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作者：
K. Wendt;T. Gottwald;C. Mattolat;S. Raeder
本文对镧系和锕系元素的原子电离势进行了系统的研究。现有的实验基础，主要依赖于共振电离光谱的结果，已扩展了新的激光光谱研究的元素Au，Dy，Pr和Pa。由于Pa原子光谱的复杂性，除Pa外，其它的电离势都能得到精确的结论性结果。然而，一个一致的解释所观察到的镧系元素和锕系元素的电离势的趋势。镧系元素在半壳层闭合上下呈现出两种众所周知的、完全平滑的线性趋势，由此推导出全放射性元素钷的电离势为IPPm= 44985（140）cm− 1。相比之下，较轻的成员的锕系元素低于半满壳表现出显着的偏离预测，这主要是由于相对论的影响，影响了大量的低洼配置的精力充沛的位置。假设在电离过程中去除6d电子，理论和实验之间的一致性和平滑，即使不是线性的行为，也得到在周期表的这个区域。这一新的解释有助于更好地预测比锕系元素重的元素的类似趋势和系统学。在这方面特别相关的是超重元素，它们只以极小的原子数产生，因此还不能用于任何原子物理学研究。
A study on the systematic of the atomic ionization potentials for both, the lanthanide and actinide elements have been performed. The existing experimental basis, predominantly relying on results from resonance ionization spectroscopy, has been extended by novel laser spectroscopic investigations on the elements Au, Dy, Pr and Pa. Conclusive results of suitable precision for the ionization potentials could be obtained except for Pa, due to the complexity of its atomic spectrum. Nevertheless, a consistent interpretation of the observed trends for the ionization potentials of lanthanides and actinides was attempted. The series of lanthanides depicts the two well-known, completely smooth, linear trends above and below half-shell closure, from which an expectation value for the missing ionization potential of the all radioactive element promethium of IPPm= 44985(140) cm−1was derived. In contrast, the lighter members of the actinide series below the half-filled shell exhibit a significant deviation from predictions, which are ascribed dominantly to relativistic influences affecting the energetic position of the multitude of low-lying configurations. With the assumption of removal of a 6d electron during the ionization process agreement between theory and experiment and a smooth, even though not linear behavior, is obtained also in this region of the Periodic Table. This new interpretation could help to better predict similar trends and systematics for elements heavier than the actinides. Particularly relevant in this respect are the super-heavy elements, which are produced only in minuscule atom numbers and thus were not accessible for any atomic physics study yet.