近日，美国劳伦斯伯克利国家实验室Jennifer L. Pore团队实现了用单原子技术直接鉴定Ac和No分子。这一研究成果发表在2025年8月4日出版的《自然》杂志上。

元素周期表为理解化学性质提供了一个直观的框架。然而，它的传统模式可能会因为占据图表底部的最重元素而崩溃。

锕系元素（Z>88）和超重元素（Z≥104）的大原子核产生了相对论效应，预计将极大地改变它们的化学行为，这可能表明研究组已经达到了预测周期表的终点。相对论效应已经被引证为锕系元素与镧系元素的化学性质不同的原因。不幸的是，很难理解相对论效应的全部影响，因为对后来的锕系元素和超重元素的研究很少。除了镄（Z = 100），其他元素需要一次生产和研究一个原子，使用加速离子束和最先进的实验方法。到目前为止，还没有实验能够直接识别产生的分子种类。

在劳伦斯伯克利国家实验室的88英寸回旋加速器设备上，锕离子（Ac, Z = 89）和铌离子（No, Z = 102）通过核反应合成，然后暴露在微量的H₂O和N₂中。用FIONA （用于识别核素A）方法直接鉴定了产物的质量电荷比。据他们所知，这些结果标志着第一次以原子-一次技术为主题的重元素分子物种的直接鉴定，并强调了这种鉴定在未来超重元素化学实验中加深对其化学性质理解的重要性。

附：英文原文

Title: Direct identification of Ac and No molecules with an atom-at-a-time technique

Author: Pore, Jennifer L., Gates, Jacklyn M., Dixon, David A., Garcia, Fatima H., Gibson, John K., Gooding, John A., McCarthy, Mallory, Orford, Rodney, Shafi, Ziad, Shuh, David K., Sprouse, Sarah

Issue&Volume: 2025-08-04

Abstract: The periodic table provides an intuitive framework for understanding chemical properties. However, its traditional patterns may break down for the heaviest elements occupying the bottom of the chart. The large nuclei of actinides (Z>88) and superheavy elements (Z≥104) give rise to relativistic effects that are expected to substantially alter their chemical behaviours, potentially indicating that we have reached the end of a predictive periodic table1. Relativistic effects have already been cited for the unusual chemistry of the actinides compared with those of their lanthanide counterparts2. Unfortunately, it is difficult to understand the full impact of relativistic effects, as research on the later actinides and superheavy elements is scarce. Beyond fermium (Z=100), elements need to be produced and studied one atom at a time, using accelerated ion beams and state-of-the-art experimental approaches. So far, no experiments have been capable of directly identifying produced molecular species. Here ions of actinium (Ac, Z=89) and nobelium (No, Z=102) were synthesized through nuclear reactions at the 88-Inch Cyclotron facility at Lawrence Berkeley National Laboratory and then exposed to trace amounts of H2O and N2. The produced molecular species were directly identified by measuring their mass-to-charge ratios using FIONA (For the Identification Of Nuclide A)3. These results mark the first, to our knowledge, direct identification of heavy-element molecular species using an atom-at-a-time technique and highlight the importance of such identifications in future superheavy-element chemistry experiments to deepen understanding of their chemical properties.

DOI: 10.1038/s41586-025-09342-y

Source: https://www.nature.com/articles/s41586-025-09342-y