NMR free induction decay and spin echoes in oriented model membrane bilayers

A method is demonstrated which produces Carr-Purcell NMR spin echoes for protons in the lamellar potassium oleate-D₂O system oriented between glass plates. When the hydrocarbon chains are oriented at an angle of cos^?1(3^{?$\text{1}\text{2}$}) with the magnetic field, the dipolar interactions are removed and the free induction decay is inhomogeneity limited. The Carr-Purcell spin echo can be obtained only at this angle. It is proposed to use this method to measure diffusion in oriented membrane systems.