Proux Olivier, Lahera Eric, Del Net William, Kieffer Isabelle, Rovezzi Mauro, Testemale Denis, Irar Mohammed, Thomas Sara, Aguilar-Tapia Antonio, Bazarkina Elena F, Prat Alain, Tella Marie, Auffan Mélanie, Rose Jérôme, Hazemann Jean-Louis
J Environ Qual. 2017 Nov;46(6):1146-1157. doi: 10.2134/jeq2017.01.0023.
The study of the speciation of highly diluted elements by X-ray absorption spectroscopy (XAS) is extremely challenging, especially in environmental biogeochemistry sciences. Here we present an innovative synchrotron spectroscopy technique: high-energy resolution fluorescence detected XAS (HERFD-XAS). With this approach, measurement of the XAS signal in fluorescence mode using a crystal analyzer spectrometer with a ∼1-eV energy resolution helps to overcome restrictions on sample concentrations that can be typically measured with a solid-state detector. We briefly describe the method, from both an instrumental and spectroscopic point of view, and emphasize the effects of energy resolution on the XAS measurements. We then illustrate the positive impact of this technique in terms of detection limit with two examples dealing with Ce in ecologically relevant organisms and with Hg species in natural environments. The sharp and well-marked features of the HERFD-X-ray absorption near-edge structure spectra obtained enable us to determine unambiguously and with greater precision the speciation of the probed elements. This is a major technological advance, with strong benefits for the study of highly diluted elements using XAS. It also opens new possibilities to explore the speciation of a target chemical element at natural concentration levels, which is critical in the fields of environmental and biogeochemistry sciences.
利用X射线吸收光谱法（XAS）研究高度稀释元素的物种形成极具挑战性，尤其是在环境生物地球化学领域。在此，我们介绍一种创新的同步辐射光谱技术：高能量分辨率荧光探测XAS（HERFD-XAS）。通过这种方法，使用能量分辨率约为1电子伏特的晶体分析仪光谱仪以荧光模式测量XAS信号，有助于克服通常使用固态探测器时对可测量样品浓度的限制。我们从仪器和光谱两个角度简要描述该方法，并强调能量分辨率对XAS测量的影响。然后，我们通过两个例子说明该技术在检测限方面的积极影响，一个例子涉及生态相关生物体中的铈，另一个例子涉及自然环境中的汞物种。所获得的HERFD-X射线吸收近边结构光谱的尖锐且明显的特征，使我们能够明确且更精确地确定被探测元素的物种形成。这是一项重大的技术进步，对使用XAS研究高度稀释元素具有很大益处。它还为在自然浓度水平下探索目标化学元素的物种形成开辟了新的可能性，这在环境和生物地球化学科学领域至关重要。
