Journal of Solution Chemistry

, Volume 34, Issue 9, pp 993–1007

A XANES and EXAFS Study of Hydration and Ion Pairing in Ambient Aqueous MnBr2 Solutions

Authors

  • Yongsheng Chen
    • Fundamental Science DivisionPacific Northwest National Laboratory
    • Fundamental Science DivisionPacific Northwest National Laboratory
  • Walter Partenheimer
    • Central Research and DevelopmentE. I. DuPont de Nemours & Co., Inc.
Article

DOI: 10.1007/s10953-005-6986-4

Cite this article as:
Chen, Y., Fulton, J.L. & Partenheimer, W. J Solution Chem (2005) 34: 993. doi:10.1007/s10953-005-6986-4

Abstract

Extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) spectroscopies were used to probe the first-shell coordination structure of Mn(II) in aqueous MnBr2 solutions at ambient conditions from very dilute to the near saturation limit. The Mn K-edge EXAFS spectra for 0.05 and 0.2 m solutions showed that there was no Br(−I) in the first shell, and that the Mn(II) was fully hydrated with six water molecules in an octahedral arrangement. In contrast, for 6 m solution, the coordination number of water was reduced to about 5, and an average of about one bromine atom was present in the first shell as a contact ion pair. The 1s → 4p transition at 6545.5 eV confirmed the observation of Mn–Br contact ion pairs at high concentrations and the 1s → 3d transition at 6539.5 eV showed that the first shell coordination symmetry remained octahedral even in the presence of Mn–Br ion pairs.

Keywords

XANESEXAFSmanganese bromideaqueous solutionhydration structure
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© Springer Science + Business Media, Inc. 2005