Low frequency and diffusive motion in aligned phospholipid multilayers studied by pulsed NMR

Measurements of T₁, T_1?, T_1D and the FID are reported for protons in aligned stacks of Egg Yolk Lecithin (EYL)-D₂O multilayers. From the ω₁ dependence of T_1? and the ω₀ dependence of T₁ the two dispersive regions of the spectral density function were identified. The lower frequency region has a centre angular frequency of 2.2 × 10⁵ rad/s and the upper frequency region a centre angular frequency of 4 × 10⁷ rad/s.From the orientation dependence of T_1?, T_1D and the FID, the lower frequency dispersion is assigned to fluctuations in the packing density of the hydrocarbon chains in the plane of the bilayer, and the upper frequency region to the translational diffusion of the lipid molecules. Based on a similar approach to one previously described, a diffusion coefficient of 1.4 × 10^?8 cm²/s is calculated for the EYL molecules in the bilayers.