Reduction of rf power of observed nuclei for 1H-homonuclear decoupled cross-polarization in solid-state NMR spectroscopy

A new approach to markedly reduce rf power for observed nuclei during 1H-homonuclear decoupled cross-polarization is described. The reduction of rf power to satisfy the Hartmann–Hahn matching condition for observed nuclei and homonuclear dipolar decoupling at 1H nuclei were achieved simultaneously based on ‘time averaging’ of nutation frequency of 1H nuclei by frequency switched Lee–Goldburg decoupling with unequal duration times for ±LG irradiations. The rf nutation frequency and rf field for observed nuclei were shown experimentally to be reduced by factor 3 and 10, respectively, at 13C-NMR signals of MBBA in the liquid crystalline state.