Time-dependent xenon diffusion measurements in microporous silicon imidonitrides by pulsed field gradient NMR spectroscopy

We present time-dependent xenon diffusion measurements over a wide range of diffusion times in three different silicon imidonitrides, a new class of microporous catalysts, by PFG NMR spectroscopy. Our experimental data show that for short diffusion times Δ a sharp decrease of the diffusion coefficient D with increasing Δ occurs, while in the long-time regime D approaches a constant value. We correlate the differences in the diffusional behaviour with the pore structure of the material. Additionally, we found that for these materials there is a linear correlation between the chemical shift of the 129Xe resonances and the corresponding long-time diffusion coefficient.