Direct observation of fractional change of niobium ionic species in a solution by means of X-ray absorption fine structure spectroscopy
Direct observation of fractional change of niobium ionic species in a solution by means of X-ray absorption fine structure spectroscopy
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DOI：
10.1002/xrs.2390
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发表时间：
2012-07
影响因子：
1.2
通讯作者：
Yuta Kubouchi;S. Hayakawa;H. Namatame;T. Hirokawa
中科院分区：
文献类型：
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作者：
Yuta Kubouchi;S. Hayakawa;H. Namatame;T. Hirokawa
采用对x射线吸收原子配位环境敏感的Nb - l3边缘x射线吸收近边缘结构（XANES）光谱研究了草酸铌在草酸溶液中的局部配位。在NbO(C2O4)2H2O−和NbO(C2O4)33−的不同摩尔分数的溶液中，测量了Nb l3边缘XANES光谱。由于NbO(C2O4)2H2O−的比例较大，pH值越低，能谱峰的能移越小。光谱形状与参比样品不同，代表了四面体和八面体配位，证实了铌位的低对称性。用密度泛函理论计算模拟了两种离子的XANES光谱，这些光谱的混合显示了溶液ph变化引起的峰移。Copyright©2012 John Wiley & Sons, Ltd。
Local coordination of niobium oxalate in oxalic acid solutions was investigated by Nb L3-edge X-ray absorption near edge structure (XANES) spectroscopy that was sensitive to the coordination environment of X-ray absorbing atoms. The Nb L3-edge XANES spectra were measured from solutions of difference pH, and the solution was composed of different molar fractions of NbO(C2O4)2H2O− and NbO(C2O4)33−. The lower energy shift of the spectral peak was observed with the lower pH that was attributed to the greater fraction of NbO(C2O4)2H2O−. The spectral shape was different from those of reference samples representing tetrahedral and octahedral coordination, and the lower symmetry of niobium site was confirmed. The XANES spectra of two ionic species were simulated with the density functional theory calculations, and the mixture of these spectra demonstrated the peak shift caused by the change of solution pH. Copyright © 2012 John Wiley & Sons, Ltd.