Small angle neutron scattering, total cross-sections and mass density measurements of concentrated NaCl and KCl solutions in H2O or D2O.
The mass densities, total cold neutron cross sections and small angle scattering of concentrated NaCl and KCl solutions in H2O or D2O (2H2O) were measured at 20 degrees C. The partial specific volumes of both salts increase with salt concentration and are significantly smaller in D2O than in H2O, showing that these salt solutions cannot be considered as isomorphous in H2O and D2O. As salt concentration increases for both salts, the total coherent cross sections for neutrons of the solutions also increase while the coherent small angle scattering decreases-observations that are consistent, respectively, with increasing correlations involving the ion and water components and a decrease in the particle number density and/or concentration fluctuations, in the solutions. Changes in incoherent scattering with salt concentration are essentially those expected from the solution compositions and densities.
Bonneté
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Institut Laue Langevin, BP 156, 38042 Grenoble Cedex 9, France; Institut de Biologie Structurale, 41 Avenue des Martyrs, 38027 Grenoble Cedex 1, France.
Zaccaï
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