A study of small molecule ingress into planar and cylindrical materials using ion beam analysis

Ion beam analysis techniques have been developed to allow profiling of small molecules diffused into materials at depths ranging from 10"-"7 to 10"-"1 m. A model DPS/PS/DPS triple-layer film and D("3He,p)"4He nuclear reaction analysis was used to test the applicability of a novel data processing program - the IBA DataFurnace - to nuclear reaction data. The same reaction and program were used to depth profile the diffusion of heavy water into cellophane. A scanning "3He micro-beam technique was developed to profile the diffusion of small molecules into both planar and cylindrical materials. The materials were exposed to liquids containing deuterium labelled molecules. A cross-section was exposed by cutting the material perpendicular to the surface and this was bombarded by a scanning "3He micro-beam. Nuclear reaction analysis was used to profile the diffusing molecules, particle induced X-ray emission (in most cases) to locate the matrix and Rutherford backscattering for normalisation. Two-dimensional maps showing the molecular distribution over the cross-section were obtained. From these one-dimensional concentration profiles were produced. Water diffusion was studied into a planar and a cylindrical polymer, three different planar fibre optic grade glasses and both a fibre optic pressure sensor and communication fibre. The diffusion of dye into hair was also investigated. These studies have provided information about the diffusion mechanisms that take place, and where relevant diffusion coefficients have been obtained using either a semi-infinite medium Fickian planar diffusion model or a cylindrical Fickian diffusion model. (author)SIGLEAvailable from British Library Document Supply Centre-DSC:DXN048990 / BLDSC - British Library Document Supply CentreGBUnited Kingdo