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

In: Chemical Physics Letters, Jg. 305 (1999) ; Nr. 1,2, S. 39-43
ISSN: 0009-2614
Zeitschriftenaufsatz / Fach: Chemie
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 exptl. data show that for short diffusion times D a sharp decrease of the diffusion coeff. D with increasing D occurs, while in the long-time regime D approaches a const. value. We correlate the differences in the diffusional behavior with the pore structure of the material. Addnl., we found that for these materials there is a linear correlation between the chem. shift of the 129Xe resonances and the corresponding long-time diffusion coeff.