HIGH-RESOLUTION NMR-SPECTROSCOPY ON ADSORBED MOLECULES IN ONE AND 2 DIMENSIONS

A considerable decrease of the line widths in the proton magnetic reso nance spectra of molecules adsorbed in zeolites is achieved by using m agic angle spinning (MAS) of sealed samples, and by reducing the influ ence of paramagnetic species in the samples. This gain in resolution e nables the application of typical techniques of one- and two-dimension al NMR spectroscopy developed for liquid-like systems also to adsorbed molecules. Thus, small relative changes of chemical shifts in H-1 NMR spectra with variing temperature and at different loadings can be obs erved. The contribution of additional longitudinal proton spin relaxat ion processes due to paramagnetic impurities could be strongly reduced what allows the detection of cross relaxation processes in the NOESY experiment. Additionally, the applicability of 2D heteronuclear correl ated magnetic resonance spectroscopy is shown for butene-1 molecules a dsorbed in zeolites revealing similar advantages for structure investi gations as known from liquid-phase NMR.