By interpolating a 4fq6s → 4fq7s transition within the sequence f1 → f14 rather than between f0 and f14, revised second ionization energies of the lanthanides have been obtained. In the early part of the series, between cerium and samarium, the revisions are significantly higher than currently accepted values. The revised values have been used to calculate the energy variation for the conversion of Ln(g, 4fq6s2) to Ln2+(g, 4fq) across the series Ba → Yb. The variation is smooth between lanthanum and ytterbium but the barium point at q = 0 is displaced downwards by more than 0.3 eV, thereby representing a significant sub-shell break. A case is also made for a substantial change to the second ionization energy of lutetium, the revised value being 14.13 ± 0.10 eV.

中文翻译：

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镧系元素电离能和亚壳断裂。第 1 部分。 第二电离能

通过在序列 f1 → f14 内而不是在 f0 和 f14 之间插入 4fq6s → 4fq7s 跃迁，已经获得了镧系元素的修正第二电离能。在系列的早期部分，在铈和钐之间，修订显着高于当前接受的值。修订后的值已用于计算从 Ba → Yb 序列中将 Ln(g, 4fq6s2) 转换为 Ln2+(g, 4fq) 的能量变化。镧和镱之间的变化是平滑的，但 q = 0 处的钡点向下位移了 0.3 eV 以上，从而代表了显着的亚壳断裂。还提出了镥的第二电离能发生实质性变化的情况，修正值为 14.13 ± 0.10 eV。