Electronic Structure of U (III) and U (IV) Ions in a LiCl-KCl eutectic melt at 450 °C
Electronic Structure of U (III) and U (IV) Ions in a LiCl-KCl eutectic melt at 450 °C
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DOI：
10.1016/j.microc.2011.05.006
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发表时间：
2012-05-01
影响因子：
4.8
通讯作者：
Song, Kyuseok
中科院分区：
文献类型：
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作者：
Cho, Young-Hwan;Bae, Sang-Eun;Song, Kyuseok
我们测量了 450 摄氏度 LiCl-KCl 共晶熔体中 U (III) 和 U (IV) 离子的电子吸收光谱，以了解它们在乏核燃料热化学过程中的光谱化学行为。 U (III) 离子的 UV-VIS 光谱由 400-600 nm 范围内的两个主峰组成，这两个主峰归因于 5f(3)-5f(2)6d(1) 跃迁。 U (III) 离子的 5f-6 d 跃迁发生在低至 400-600 nm 范围的较低能量下，而 Nd (III) 和 U (IV) 离子的 5f-6 d 跃迁发生在正常紫外范围内更高的能量下。对于 U (III) 离子，5f-5f 跃迁的强度比镧系元素中的 4f-4f 跃迁的强度大约大一个数量级。 5f-6d 跃迁比镧系离子的 4f-5d 跃迁小大约一个数量级。估算 U (III)、U (IV) 和 Nd (III) 离子的电子能级以了解它们的电子跃迁。 U(III)、Nd(III)、U(IV)离子的电子吸收光谱的特征可以通过其电子结构合理地解释。对高温LiCl-KCl中U(III)U(VI)氧化还原反应的原位监测表明该氧化还原反应是可逆的。 (C) 2011 Elsevier B.V. 保留所有权利。
We have measured the electronic absorption spectra of the U (III) and U (IV) ions in a LiCl-KCl eutectic melt at 450 degrees C to understand their spectrochemical behavior in the context of pyrochemical process of spent nuclear fuel. The UV-VIS spectra of the U (III) ion consist of two main peaks in the range of 400-600 nm which are attributable to the 5f(3)-5f(2)6d(1) transitions. The 5f-6 d transitions of U (III) ion occurred at lower energy as low as 400-600 nm range while that of Nd (III) and U (IV) ion occur at much higher energy over the normal UV range. For the U (III) ion, the intensities of 5f-5f transitions are about one order of magnitude larger than the 4f-4f transitions in lanthanides. And the 5f-6 d transitions are about one order of magnitude smaller than in the 4f-5 d transitions in the lanthanide ions. The electronic energy levels of the U (III), U (IV) and Nd (III) ions are estimated to understand their electronic transitions. The features of the electronic absorption spectra of U (III), Nd (III), U (IV) ions are reasonably explainable by their electronic structure. In-situ monitoring of the U (III) U (VI) redox reaction in a high temperature LiCl-KCl showed that the redox reaction is reversible. (C) 2011 Elsevier B.V. All rights reserved.