0000000000371308
AUTHOR
R. M. Kenn
Behenic Acid as a Structural Model for Fatty Acid Monolayers at the Air/Water Interface: An X-Ray Diffraction Study
We present an X-ray diffraction study of behenic (docosanoic) acid films at the air/water interface. Analysis of the rod profiles parallel and perpendicular to the surface provides detailed information on the unit cells of five different phases.
The Phases of Phosphatidyl Ethanolamine Monolayers
For the first time phospholipid monolayers at the air/water interface have been studied by X-ray diffraction and reflection along the whole isotherm from the isotropic fluid to the ordered phases [1]. The model used to analyze the data — and the accuracy of the parameters deduced — were tested by comparing the results obtained with two lipids having the same head group but different chain lengths.
Monolayers of Amphiphilic Molecules
There are good reasons why the organizers have placed this lecture at the beginning of a conference on the multip1e aspects of membranes. In many respects the monolayer may be considered half of a membrane and it obviously is the most simple and best-defined model system. Yet we will show that the system is more complex than many have anticipated. On the other hand, there are many general features which can be discussed without looking into chemical details.
Tilted phases of fatty acid monolayers
X‐ray diffraction data from water‐supported monolayers of fatty acids with chain lengths from 19 to 22 is presented. The structures of the tilted mesophases L2’, L2, and Ov are characterized in detail. The contributions to the unit cell distortion from the tilt and the ordering of the backbone planes of the molecules are separated. It is shown that at the swiveling transition L2’–L2, not only the tilt azimuth but also the packing of the backbone planes change discontinuously. We demonstrate that the tilting transition LS–L2 is accompanied by the ordering of the backbone planes and may be discontinuous. Evidence is presented for a herringbone ordering transition within the L2 region. The dis…
Thickness and temperature dependent structure of Cd arachidate Langmuir-Blodgett films
Abstract The structure of monolayers of Cd arachidate on water and on solid support, and the thickness dependent changes when building up a multilayer via the LB technique are studied by means of grazing incidence diffraction of X-ray. In monolayers the perpendicularly oriented amphiphilic molecules are arranged in a hexagonal lattice, whereas for thicker layers (even for three layers) they crystallize in an orthorhombic unit cell with a reduced molecular are ( A = 18.2 A 2 ) compared to that of the monolayer ( A = 19.7 A 2 ). In-plane diffraction measurements with wave vector transfer perpendicular to the surface (rod scans) could prove for multilayers a maximum tilt angle of 2°. The data …
X-ray scattering studies of fatty acid films on water and on Cdcl2 solutions
X-ray diffraction methods for Langmuir films on the surface of water are briefly presented, together with recent results for docosanoic acid monolayers on pure water and for eicosanoic acid monolayers on an ionic subphase.
X-Ray Scattering Studies of Organic Monolayers on Electrolytic Solutions: Arachidic Acid on CdCl2
The interaction between a charged monolayer of fatty acid molecules on the surface of a CdCl2 aqueous solution and the ions below has been investigated by means of X-ray Reflection and Grazing-Incidence Diffraction. A stoichiometric, localised layer of Cd++ ions forms an epitaxial 2×3 superstructure below the 2D-crystalline fatty acid monolayer.