Frequency-switched Lee-Goldburg decoupling

A new approach to markedly reduce RF power for observed nuclei during H-homonuclear decoupled CP has been described Nishimura and Naito. The reduction of RF power to satisfy the Hartmann-Hahn matching condition for observed nuclei and homonuclear dipolar decoupling at H nuclei were achieved simultaneously based on time averaging of nutation frequency of H nuclei by frequency switched Lee-Goldburg decoupling with unequal duration times. The RF nutation frequency and RF field for observed nuclei were shown experimentally to be reduced by factor 3 and 10, respectively, at NMR signals. 

Figure 13 Pulse sequence for the solid-state 31P—1H frequency-switched Lee-Goldburg (FSLG) experiment. Proton-proton homonuclear decoupling was performed by using the FSLG decoupling sequence. Quadrature detection in Wi was achieved by using the TPPI method. During the acquisition period, TPPM heteronuclear decoupling was applied.

In this section, we consider windowless homonuclear decoupling sequences. Specific examples are the Lee—Goldburg (LG) technique [101] and refinements, namely the frequency switched and phase-modulated LG (FSLG [102, 103] and PMLG [104]) sequences, as well as the computer-optimised sequence, DUMBO-1... 

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