Raman spectroscopy and local order in aqueous solutions of strong II–I electrolytes

Abstract

We report polarized Raman spectra for aqueous solutions of NiCl2, CdCl2, ZnCl2, CuCl2, Cu(NO3)2, and SrCl2. Our analysis of the Raman data provides an interpretation for the diffuse low frequency Raman scattering in transition metal halide–water solutions in terms of a vibrational density of states. Such a density corresponds to collective vibrational modes in a solute-connected middle range lattice. The results are also discussed on the basis of recent measurements of viscosity, thermodynamic quantities, and EXAFS.