The time-domain analysis of nuclear resonant scattering (NRS) of X-rays was applied to the study of the hydrogen-induced enhancement of atomic diffusion. The time-domain analysis of NRS was a powerful technique for studying diffusion processes on an atomic scale. The NRS measurement combined with high-pressure technique enables the direct measurement of self-diffusion processes under high hydrogen pressures. In this preliminary experiment, self-diffusion in 4 μm thick 57Fe foils at 0.8 GPa was investigated. The samples of the 57Fe were encapsulated with MgO or NaCl. Faster decays caused by diffusion of Fe atoms were observed in the time spectra of NRS at high temperatures. This enhancement of diffusion was believed to be the hydrogen-induced effect. In the present experiment, hydrogen should were supplied to the samples by reaction with water originally adsorbed on NaCl/MgO powder particles. It was concluded that the diffusion of 57Fe atoms under high pressure could be studied by nuclear resonant scattering of X-rays using a compact cubic-anvil press. The NRS method could also be extended to the study of atomic diffusion in the subsurface region by doping 57Fe layer(s) at known depths.

Measurement of Diffusion Process of Iron Atoms under High Pressure of Hydrogen by Time-Domain Analysis of Nuclear Resonant Scattering of X-rays. H.Kasai, T.Kawauchi, Y.Fukai, X.W.Zhang, S.Kishimoto, T.Kikegawa, E.Ohtani, T.Okano: Applied Surface Science, 2009, 256[4], 984-6