Evidence of a local order in concentrated aqueous solutions of salts constituted by ions of different valences

We revisit the fact that aqueous ionic solutions containing cations of higher valences than that of the anions display features in their X-ray patterns, which have been interpreted in terms of a medium range order between the cations. Additional evidence is derived from Raman spectroscopy about the...

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Bibliographic Details
Published inJournal of molecular liquids Vol. 134; no. 1; pp. 142 - 150
Main Authors Marques, M. Alves, de Barros Marques, M.I., Cabaço, M. Isabel, Gaspar, A.M., Marques, M.P.M., Amado, A.M., Amorim da Costa, A.M.
Format Journal Article
LanguageEnglish
Published Elsevier B.V 01.05.2007
Subjects
Ion
Raman spectroscopy
Valence
X-ray diffraction
X-ray diffraction
Ion
Valence
Raman spectroscopy
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Summary:We revisit the fact that aqueous ionic solutions containing cations of higher valences than that of the anions display features in their X-ray patterns, which have been interpreted in terms of a medium range order between the cations. Additional evidence is derived from Raman spectroscopy about the degeneracy removal in vibrational spectra of the nitrate anion. Inelastic neutron scattering experiments permitted to demonstrate the existence of characteristic modes in cation hydrates. Model calculations, assuming independent vibrational species, are in agreement with a medium range order of the cations. We show also that a similar, but weaker, ordering arises if the anions are of higher valence than the cations.
ISSN:0167-7322
1873-3166
DOI:10.1016/j.molliq.2006.12.007