近日，美国劳伦斯伯克利国家实验室Rebecca J. Abergel、Corwin H. Booth以及洛斯阿拉莫斯国家实验室Stosh A. Kozimor课题组实现了锿络合物的结构和光谱表征。 相关论文于2021年2月3日发表于国际顶尖学术期刊《自然》杂志上。

在这里，课题组研究人员描述了一个以有机羟基吡啶酮为基础的螯合配体的锿络合物，使用少于200纳克的²⁵⁴Es（半衰期为275.7(5)天）。研究人员利用X射线吸收光谱和结构研究，确定L₃边缘的能量和锿的键距。

光物理测量表明Es^III发光的天线敏化效应；他们还揭示了金属络合的低色转移，这以前在低原子数锕系元素中没有观察到。

这些发现表明了一个自旋轨道耦合的中间态，其中j - j耦合（其中单电子轨道角动量和自旋首先耦合形成总角动量j）优于Rthemsell-Saunders耦合。与之前的锕系络合作用研究一起，他们的结果强调了继续研究锕系元素的异常行为的必要性，特别是那些稀缺和短寿的元素。

研究人员表示，超钚元素（原子序数95-103）是位于元素周期表边缘的一组金属。因此，用于预测和控制过渡金属、主族元素和镧系元素的物理和化学性质的模式和趋势不适用于超钚元素。

此外，这些重元素的稀缺性和放射性限制了人们对其性质的理解。这对锿来说尤其如此，它是元素周期表中目前可以产生足够的量来支持经典的宏观尺度研究的最重的元素。

附：英文原文

Title: Structural and spectroscopic characterization of an einsteinium complex

Author: Korey P. Carter, Katherine M. Shield, Kurt F. Smith, Zachary R. Jones, Jennifer N. Wacker, Leticia Arnedo-Sanchez, Tracy M. Mattox, Liane M. Moreau, Karah E. Knope, Stosh A. Kozimor, Corwin H. Booth, Rebecca J. Abergel

Issue&Volume: 2021-02-03

Abstract: The transplutonium elements (atomic numbers 95–103) are a group of metals that lie at the edge of the periodic table. As a result, the patterns and trends used to predict and control the physics and chemistry for transition metals, main-group elements and lanthanides are less applicable to transplutonium elements. Furthermore, understanding the properties of these heavy elements has been restricted by their scarcity and radioactivity. This is especially true for einsteinium (Es), the heaviest element on the periodic table that can currently be generated in quantities sufficient to enable classical macroscale studies. Here we characterize a coordination complex of einsteinium, using less than 200 nanograms of ²⁵⁴Es (with half-life of 275.7(5) days), with an organic hydroxypyridinone-based chelating ligand. X-ray absorption spectroscopic and structural studies are used to determine the energy of the L₃-edge and a bond distance of einsteinium. Photophysical measurements show antenna sensitization of Es^III luminescence; they also reveal a hypsochromic shift on metal complexation, which had not previously been observed in lower-atomic-number actinide elements. These findings are indicative of an intermediate spin–orbit coupling scheme in which j–j coupling (whereby single-electron orbital angular momentum and spin are first coupled to form a total angular momentum, j) prevails over Russell–Saunders coupling. Together with previous actinide complexation studies, our results highlight the need to continue studying the unusual behaviour of the actinide elements, especially those that are scarce and short-lived.

DOI: 10.1038/s41586-020-03179-3

Source: https://www.nature.com/articles/s41586-020-03179-3