| Popis: |
A new method for performing multiple-quantum NMR experiments is described. Instead of incrementing the evolution period t1 in the conventional manner, t1 is kept fixed while the magnetic field is increased, successively. The method is illustrated using 19F spins in dipolar coupled 2,2-difluorotetrachloroethane, 1,1,1 -trichlorotrifluoroethane, and hexafluorobenzene, oriented in a nematic liquid crystal. It is demonstrated that Zeeman-incremented multiple-quantum NMR experiments give rise to simplified spectra in the multiple-quantum t1 domain, free from T2 decay. For example, in the case of hexafluorobenzene, just seven equally spaced peaks are observed, corresponding to Δm = ± 0, 1, . . . , 6. |
