Electron diffractionElectron diffraction refers to changes in the direction of electron beams due to interactions with atoms. Close to the atoms the changes are described as Fresnel diffraction; far away they are called Fraunhofer diffraction. The resulting map of the directions of the electrons far from the sample (Fraunhofer diffraction) is called a diffraction pattern, see for instance Figure 1. These patterns are similar to x-ray and neutron diffraction patterns, and are used to study the atomic structure of gases, liquids, surfaces and bulk solids.
Powder diffractionPowder diffraction is a scientific technique using X-ray, neutron, or electron diffraction on powder or microcrystalline samples for structural characterization of materials. An instrument dedicated to performing such powder measurements is called a powder diffractometer. Powder diffraction stands in contrast to single crystal diffraction techniques, which work best with a single, well-ordered crystal. Diffraction grating The most common type of powder diffraction is with x-rays, the focus of this article although some aspects of neutron powder diffraction are mentioned.
Ether lipidIn an organic chemistry general sense, an ether lipid implies an ether bridge between an alkyl group (a lipid) and an unspecified alkyl or aryl group, not necessarily glycerol. If glycerol is involved, the compound is called a glyceryl ether, which may take the form of an alkylglycerol, an alkyl acyl glycerol, or in combination with a phosphatide group, a phospholipid. In a biochemical sense, an ether lipid usually implies glycerophospholipids of various type, also called phospholipids, in which the sn-1 position of the glycerol backbone has a lipid attached by an ether bond and a lipid attached to the sn-2 position via an acyl group.
