Nuclear resonant quasielastic scattering from Fe cations in Nafion membranes: Effect of dynamics in a short time range

The effect of the diffusive motion in a short time range on the nuclear res onant quasielastic scattering spectrum is presented. The solution of the La ngevin equation, which describes the motion of the diffusing particle in a short time range as well as that in a long time range, was applied to analy ze the nuclear resonant scattering spectrum of Fe cations in Nafion membran es instead of the solution of the generally-used simple diffusion equation which does not describe the diffusive motion in a short time range correctl y. It made improvements in the fitting especially at the wings of the data as compared with the solution of the simple diffusion equation. The charact eristic time of the diffusive motion of Fe ions in Nafion is estimated to h e about 10(-14) s. By the detailed analysis of the high energy part of nucl ear resonant scattering spectrum, it is possible to reveal diffusive motion even in the short time range as similar to 10(-14) s.