| The dynamics of transport processes, such as hydrogen transport in metals, can only be obtained from non-steady state techniques. We have derived the relevant expressions for the phase shift and magnitude of the transfer function describing the response to a modulated hydrogen flux at the entry surface of a thin film. The expressions include the influence of trapping, surface, multilayer and interface effects. Steady state rising and decaying transients have also been recorded. Experiments have been carried out on iron and palladium monolithic foils, iron-palladium multilayers and nanoparticulate palladium containing iron films on iron-palladium bilayers. Accurate diffusion coefficients have been obtained. Palladium has been shown to form β Pd-H when present at the entry surface. The effect of the palladium-iron interface has been shown to be significant. Nanoparticulate has shown a tremendous ability to getter hydrogen as evidenced by the steady state and dynamic permeation measurements as well as measurements taken via nuclear reaction analysis. |
