DYNAMICS OF THE SULFATE ION IN DILUTE WATER-DMF SOLUTIONS

The Raman band of the nu(1)(A(1)) mode of SO42- of Li2SO4 dissolved in water and water-dimethylformamide mixtures was measured in the concentration range 0.01 to 0.2 mol.dm(-3). The central frequency of the sulfate ion increases with sulfate concentration. The limiting frequency at infinite dilution depends on the DMF content. The Raman band becomes asymmetric with increasing concentration of Li2SO4 in 20 wt% DMF mixtures and with addition of LiCl to the aqueous solution of Li2SO4. The vibrational relaxation behavior of the nu(1)(A(1)) mode was investigated by analyzing the vibrational correlation function based on Kubo's stochastic theory.