High-sensitive XANES analysis at Ce L2-edge for Ce in bauxites using transition-edge sensors: Implications for Ti-rich geological samples
High-sensitive XANES analysis at Ce L2-edge for Ce in bauxites using transition-edge sensors: Implications for Ti-rich geological samples
复制标题
使用过渡边缘传感器在 Ce L2 边缘对铝土矿中的 Ce 进行高灵敏度 XANES 分析：对富钛地质样品的影响
DOI：
10.1016/j.aca.2022.340755
复制
发表时间：
2023
影响因子：
6.2
通讯作者：
et al.
中科院分区：
文献类型：
--
作者：
Li Wenshuai;Yamada Shinya;et al.
铈价态的准确测定对于解释地质档案中的铈异常、恢复古氧化还原环境具有重要意义。然而，常规应用Ce L3边X射线吸收近边结构（XANES）光谱检测地质样品中的痕量Ce，往往会受到共存的钛（Ti）的限制，由于它们的荧光发射线的接近。因此，Ce L3边缘XANES光谱的信噪比对于高质量光谱分析可能不够高。本研究介绍了一种半定量的方法，适用于富钛，铈稀地质材料的同步加速器为基础的X射线测量在Ce的L2边缘。首先，结果证实Ce L2边XANES光谱能够避免重叠Ti Kβ发射，并且相对于L3边XANES提供关于富Ti材料中Ce价态的更可靠的信息。此外，与传统的硅漂移探测器（SDD）相比，过渡边传感器（TES）可以获得更高的灵敏度和更好的能量分辨率来探测荧光X射线（Ce Lβ1）。对哥伦比亚河玄武岩中铝土矿的研究表明，将Ce L2边XANES和TES相结合，可以分辨出富Ti、稀Ce样品（Ti/Ce质量比高达6000，Ce含量为几十ppm）L2边的弱Ce荧光线。这一结果强调了研究富钛地质样品中铈氧化还原状态的实际可能性。
Accurate determination of cerium (Ce) valence state is important for interpreting the Ce anomaly in geological archives for (paleo)redox reconstruction. However, the routine application of Ce L3-edge X-ray absorption near-edge structure (XANES) spectroscopy for detecting trace Ce in geological samples can often be restricted by coexisting titanium (Ti) due to the proximity of their fluorescence emission lines. Therefore, the signal-to-noise ratio of Ce L3-edge XANES spectra may not be sufficiently high for high-quality spectroscopic analysis. This study introduces a semi-quantitative approach appropriate for Ti-rich, Ce-dilute geological materials by synchrotron-based X-ray measurement at the Ce L2-edge. First, the results confirm that Ce L2-edge XANES spectra are able to avoid overlapping Ti Kβemissions and provide more reliable information on the Ce valence state in Ti-rich materials relative to L3-edge XANES. Moreover, the application of transition-edge sensor (TES) could reach the higher sensitivity with better energy resolution than conventional silicon drift detector (SDD) to detect fluorescence X-ray (Ce Lβ1). The investigation on bauxites developed from the Columbia River Basalts shows that combining Ce L2-edge XANES and TES allows for resolving weak Ce fluorescence lines at the L2-edge from Ti-rich, Ce-dilute samples (Ti/Ce mass ratio up to ∼6000, tens of ppm Ce). The outcome emphasizes the practical possibility of investigating Ce redox state in Ti-rich geological samples.