Dramatic reduction of the RF power for attenuation of sample heating in 2D-separated local field solid-state NMR spectroscopy

A new method for two-dimensional separated local field solid-state NMR spectroscopy was developed. By applying a time averaging effect for the nutation frequency in the tilted rotating frame, which we proposed recently, a large reduction of the RF power for observed nuclei during the spin exchange period can be achieved without impairing the 1H homonuclear dipolar decoupling efficiency. The reduction of the RF nutation frequency and the RF field for observed nuclei during the spin exchange period were achieved experimentally as 1/3 and 1/9, respectively, for the 13C NMR signals of liquid-crystalline 5CB. Consequently, effective attenuation of sample heating was obtained.