Imaging of the H-1 NMR second moment with C-13 chemical-shift resolution

A method of C-13 chemical-shift-resolved H-1 second moment imaging is propo sed for molecular mobility imaging of heterogeneous materials. For evaluati ng the H-1 second moment, the method relies on the curve fitting procedure using spin-echo shapes indirectly: The information of 1H echo shapes is tra nsferred to the C-13 signal amplitude through H-1-C-13 cross polarization a nd then the curve fitting is made using the C-13 signal amplitude. The C-13 signal is detected under H-1 dipolar decoupling and magic angle spinning, resulting in the incorporation of C-13 chemical-shift resolution. Imaging i nformation is included in the C-13 signal by application of phase-encoding gradients. The second moment images obtained can reflect the molecular mobi lity at every molecular site separated by C-13 chemical shifts, yielding de tailed information on the molecular mobility, The method is demonstrated by spatially 1D experiments performed on a model sample. (C) 2000 Academic Pr ess.