The study of slow coherent molecular motion by pulsed nuclear magnetic resonance

Abstract

The effect of coherent molecular motion, e.g. flow, on pulsed nuclear magnetic resonance experiments is investigated theoretically. New pulse sequences are proposed which enable coherent velocities of the order of 10^-3 cm s^-1 to be measured. Equations are derived for spin-echo amplitudes in the new pulse sequence taking into account both random (self-diffusion) and coherent (flow) motion. Experiments are reported which confirm the predictions of the equations and some possible applications are discussed.