Determination of the Eu(II)/Eu(III) ratios in minerals by X-ray absorption near-edge structure (XANES) and its application to hydrothermal deposits
Determination of the Eu(II)/Eu(III) ratios in minerals by X-ray absorption near-edge structure (XANES) and its application to hydrothermal deposits
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DOI：
10.1180/0026461056920245
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发表时间：
2005-04-01
影响因子：
2.7
通讯作者：
Shimizu, H
中科院分区：
文献类型：
--
作者：
Takahashi, Y;Kolonin, GR;Shimizu, H
利用铕L-III边X射线吸收近边结构（XANES）测定了矿物中Eu（II）/Eu（III）比值。该比率可以基于Eu（II）和Eu（111）物质的归一化XANES光谱中的白色线（共振峰）的峰面积比来确定。然而，为了精确测定Eu（II）/Eu（III）比率，揭示了系统中每个单独的Eu（II）和Eu（III）物质的跃迁概率必须被量化，因为我们发现归一化XANES光谱中的峰面积在每个Eu（II）和Eu（III）物质中是不同的。尽管这种模糊性，该方法被应用于天然热液磷灰石（Eu = 39和64 ppm）和氟铈矿（Eu = 282 ppm）的Eu。并结合稀土元素配分模式中的Eu异常，讨论了这些热液矿物中Eu（II）/Eu（III）比值与Eu（II）和Eu（III）分配系数的关系。认为结合XANES测定的Eu（II）/Eu（III）比值和稀土配分模式中Eu的异常程度，可以为各种地球化学研究提供Eu（II）和Eu（III）分布的新信息。
Europium L-III-edge X-ray absorption near-edge structure (XANES) was employed to determine the Eu(II)/Eu(III) ratios in minerals. This ratio can be determined based on the peak-area ratio of white lines, the resonance peak, in normalized XANES spectra for Eu(II) and Eu(111) species. For precise determination of the Eu(II)/Eu(III) ratios, however, it was revealed that the transition probabilities for each individual Eu(II) and Eu(III) species in the system must be quantified, because we found that the peak area in normalized XANES spectra is different in each Eu(II) and Eu(III) species. Despite this ambiguity, the method was applied to Eu in natural hydrothermal apatites (Eu = 39 and 64 ppm) and fluocerite (Eu = 282 ppm). The relationship between the Eu(II)/Eu(III) ratio in these hydrothermal minerals, and the distribution coefficients of Eu(II) and Eu(III) were discussed, taking into account Eu anomalies in their REE patterns. It is considered that by combining the Eu(II)/Eu(III) ratios determined by XANES and the degree of Eu anomaly in REE patterns, we can provide new information on the distribution of Eu(II) and Eu(III) in various geochemical studies.