• 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Chemistry: A European journal >Photoluminescence of uranium(VI): Quenching mechanism and role of uranium(V)
【24h】

Photoluminescence of uranium(VI): Quenching mechanism and role of uranium(V)

机译：铀（VI）的光致发光：铀（V）的猝灭机理和作用

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The photoluminescence of uranium(VI) is observed typically in the wavelength range 400-650 nm with the lifetime of several hundreds us and is known to be quenched in the presence of various halide ions (case A) or alcohols (case B). Here, we show by density functional theory (DFT) calculations that the quenching involves an intermediate triplet excited state that exhibits uranium(V) character. The DFT results are consistent with previous experimental findings suggesting the presence of photoexcited uranium(V) radical pair during the quenching process. In the ground state of uranyl(VI) halides, the ligand contributions to the highest occupied molecular orbitais increase with the atomic number (Z) of halide ion allowing larger ligand-to-metal charge transfer (LMCT) between uranium and the halide ion. Consequently, a larger quenching effect is expected as Z increases. The quenching mechanism is essentially the same in cases A and B, and is driven by an electron transfer from the quencher to the UO_2~(2+) entity. The relative energetic stabilities of the triplet excited state define the "fate" of uranium, so that in case A uranium(V) is oxidized back to uranium(VI), while in case B uranium remains as pentavalent.
机译：铀（VI）的光致发光通常在400-650 nm的波长范围内观察到，寿命为数百us，并且已知在各种卤化物离子（情况A）或醇（情况B）的存在下会被淬灭。在这里，我们通过密度泛函理论（DFT）计算表明，淬灭涉及中间三重态激发态，表现出铀（V）特性。 DFT结果与先前的实验结果一致，表明在淬灭过程中存在光激发铀（V）自由基对。在铀酰（VI）卤化物的基态下，配体对最高占据分子轨道的贡献随着卤化物离子的原子数（Z）的增加而增加，从而允许铀与卤化物离子之间发生较大的配体到金属的电荷转移（LMCT）。因此，随着Z的增加，期望更大的淬灭效果。情况A和B的淬灭机理基本相同，并且受电子从淬灭剂转移到UO_2〜（2+）实体的驱动。三重激发态的相对能量稳定性定义了铀的“命运”，因此，在A铀（V）氧化回铀（VI）的情况下，而B铀保持五价态。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号