Proton spin-lattice relaxation in aqueous ionic solutions

The proton spin-lattice relaxation time, T 1, has been measured for aqueous solutions of sodium, potassium, rubidium and magnesium chlorides up to a concentration of about 4N at 25°c. The sodium and the magnesium chloride solutions were also measured at 60°c and 100°c. The variation of 1/T 1 is not linear with concentration, at least above about ¼N, in contrast with previous reports [1, 2]. The behaviour depends markedly on the nature of the salt and on the temperature. It is shown that almost the whole of the variation of T 1 as compared with that of water can be directly and simply related to the corresponding changes in the shear viscosity of the solutions. It is noted that the viscosity correction is better the higher the temperature of the solution.