Nuclear Resonant Quasielastic Scattering from Fe Cations in Nafion Membranes: Effect of Dynamics in a Short Time Range

Abstract

The effect of the diffusive motion in a short time range on the nuclear resonant quasielastic scattering spectrum is presented. The solution of the Langevin 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 analyze the nuclear resonant scattering spectrum of Fe cations in Nafion membranes instead of the solution of the generally-used simple diffusion equation which does not describe the diffusive motion in a short time range correctly. It made improvements in the fitting especially at the wings of the data as compared with the solution of the simple diffusion equation. The characteristic time of the diffusive motion of Fe ions in Nafion is estimated to be about 10^-14 s. By the detailed analysis of the high energy part of nuclear resonant scattering spectrum, it is possible to reveal diffusive motion even in the short time range as ∼10^-14 s.