X-RAY-DIFFRACTION STUDIES OF LECITHIN BILAYERS

The intensities were measured of Bragg reflections of X-rays from oriented periodic lamellar arrays of lecithin bilayers. The variation of the intensities with swelling of the lamellar system as H2O content increased was used to assign phases to the diffraction spectra. The assignment procedure needed to be an extension of the standard method, since the bilayer thickness decreased as the specimen swelled. Electron density profiles for bilayers of dipalmitoyl and egg lecithin were derived.