Neutron incoherent scattering law for restricted diffusion inside a volume with an anisotropic shape

Abstract
The neutron incoherent scattering law for diffusion inside a finite volume with an anisotropic shape is studied, and applied to the problem of water mobility in an acid nation® membrane containing c. 15 per cent water by weight. Both theoretical considerations and experiment show that the water molecules are diffusing practically as fast as in bulk water within roughly isotropic volumes of c. 10 Å in diameter.