Nuclear spin-lattice relaxation times of alkali metal counterions at micellar interfaces

Abstract

Spin lattice relaxation rates of Li⁺, Na⁺, Rb⁺ and Cs⁺ have been measured by pulsed n.m.r. in both simple electrolyte solutions and solutions containing surfactant micelles. Relaxation rates for the ions adsorbed at the micellar interface were greater than in simple electrolyte solutions the increase being in the order Cs⁺ > Rb⁺ > Na⁺ > Li⁺ for alkyl sulphate micelles. Distortion of the ionic hydration layer is discussed as a possible mechanism for the changes in relaxation rates.