Raman spectral studies on solutions of lithium bromide in binary mixtures of water and acetonitrile in the C---H and C≡N stretching regions

Abstract

Raman spectra of solutions of LiBr in mixtures of acetonitrile and water of varying compositions are reported. The symmetric C---H stretching and C≡N stretching bands of acetonitrile are used as probes to study the ion molecular interactions. The full width at half maximum (FWHM) and frequency shifts of the bands under consideration are analysed. Vibrational correlation functions for the CH₃ stretching mode are computed and vibrational relaxation times are evaluated for additional information. The results are explained on the basis of ion-molecular interactions in general and preferential solvation of Br^- ions by water in particular.