Research article

Direct observation of fractional change of niobium ionic species in a solution by means of X-ray absorption fine structure spectroscopy

  1. Yuta Kubouchi1,
  2. Shinjiro Hayakawa1,*,
  3. Hirofumi Namatame2,
  4. Takeshi Hirokawa1

Article first published online: 20 APR 2012

DOI: 10.1002/xrs.2390

Issue

X‐Ray Spectrometry

X-Ray Spectrometry

Special Issue: Novel methods of X-ray generation

Volume 41, Issue 4, pages 259–263, July/August 2012

Additional Information

How to Cite

Kubouchi, Y., Hayakawa, S., Namatame, H. and Hirokawa, T. (2012), Direct observation of fractional change of niobium ionic species in a solution by means of X-ray absorption fine structure spectroscopy. X-Ray Spectrom., 41: 259–263. doi: 10.1002/xrs.2390

Author Information

  1. 1

    Department of Applied Chemistry, Hiroshima University, Hiroshima, Japan

  2. 2

    Hiroshima Synchrotron Radiation Center, Hiroshima University, Hiroshima, Japan

*Shinjiro Hayakawa, Department of Applied Chemistry, Graduate School of Engineering, Hiroshima University, Higashi-hiroshima, Hiroshima 739-8527, Japan. E-mail: hayakawa@hiroshima-u.ac.jp

Publication History

  1. Issue published online: 21 JUN 2012
  2. Article first published online: 20 APR 2012
  3. Manuscript Accepted: 19 FEB 2012
  4. Manuscript Revised: 8 FEB 2012
  5. Manuscript Received: 24 DEC 2011

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Keywords:

  • XAFS;
  • L3-edge;
  • niobium;
  • DFT calculation;
  • solution

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.

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