ROTATIONAL RESONANCE WITH MULTIPLE-PULSE SCALING IN SOLID-STATE NUCLEAR-MAGNETIC-RESONANCE

Multiple-pulse techniques are applied to rotational resonance experime nts in solid-state nuclear magnetic resonance. The usual rotational re sonance condition is satisfied when an integral multiple of the magic- angle spinning speed equals the difference in isotropic chemical shift s of the two members of a homonuclear spin-1/2 pair. We show that sequ ences of rapid periodic radio-frequency pulses scale and rotate both t he Zeeman and dipole-dipole Hamiltonians, leading to a modification of the resonance condition and to the introduction of new, single- and d ouble-quantum, rotational resonances. Experimental results are present ed which demonstrate these effects in the spectra of doubly C-13-label ed solids.