Bilayer thickness estimations with “poor” diffraction data

Abstract

The lamellar fluid phase (smectic A) is the biologically most relevant membrane structure and is extensively studied by x-ray (neutron) diffraction. However, either due to experimental limitations or due to lattice disorder bilayer diffraction pattern display often not more than 2–3 diffraction orders, and hence basic parameters like membrane thickness and equilibrium intermembrane distances are not readily available. In this report is shown, how the combination of a simple bilayer model with Fourier synthesis leads to a robust estimation of the bilayer thickness. In particular, it is demonstrated how with rather simple mathematical means two and three peak diffraction pattern can be exploited.