近日，中国科学技术大学Lu, Z.-T.团队报道了原子计数法探测10-21丰度水平的大气42Ar。2026年4月14日出版的《自然—物理学》杂志发表了这项成果。
加速器质谱法所能达到的最低可探测丰度，至今仍受限于原子及分子同量异位素以及邻近同位素持续存在的背景干扰。而基于激光的原子阱痕量分析技术，通过共振光子散射逐个捕获原子，能够消除此类干扰。其探测极限仅取决于原子计数率和数据采集时长。
研究组通过将原子阱痕量分析与同位素预富集过程相结合，报告了在10-21同位素丰度水平上对大气中42Ar的直接探测，实现了比现有方法高出数个数量级的探测极限。该测量仅消耗了10升标准温压条件下的氩气。这一结果展示了一种强有力工具，可用于探测以往无法达到的丰度水平的同位素，并对环境定年以及下一代液氩探测器的背景表征具有重要意义。
附：英文原文
Title: Detection of atmospheric 42Ar at the 1021 level by atom counting
Author: Wan, Z.-F., Liang, J. W., Jia, Z. H., Jiang, W., Lu, Z.-T., Sun, L. T., Yang, G. M.
Issue&Volume: 2026-04-14
Abstract: The lowest detectable abundances with accelerator mass spectrometry remain limited by persistent background interferences from atomic and molecular isobars as well as neighbouring isotopes. Such interference is eliminated by laser-based atom trap trace analysis that captures individual atoms through resonant photon scattering. Its detection limit solely depends on the atom counting rate and data acquisition duration. Here we report the direct detection of atmospheric 42Ar at an isotopic abundance level of 1021 by combining atom trap trace analysis with an isotope pre-enrichment process, achieving a detection limit several orders of magnitude beyond existing methods. Our measurement consumed only 10l of argon at standard temperature and pressure. This result demonstrates a powerful tool for detecting isotopes at previously inaccessible abundance levels, with implications for environmental dating and background characterization in next-generation liquid-argon detectors.
DOI: 10.1038/s41567-026-03257-9
Source: https://www.nature.com/articles/s41567-026-03257-9