Rotational resonance with multiple-pulse scaling in solid-state nuclear magnetic resonance

Abstract

Multiple‐pulse techniques are applied to rotational resonance experiments in solid‐state nuclear magnetic resonance. The usual rotational resonance condition is satisfied when an integral multiple of the magic‐angle spinning speed equals the difference in isotropic chemical shifts of the two members of a homonuclear spin‐1/2 pair. We show that sequences of rapid periodic radio‐frequency pulses scale and rotate both the Zeeman and dipole–dipole Hamiltonians, leading to a modification of the resonance condition and to the introduction of new, single‐ and double‐quantum, rotational resonances. Experimental results are presented which demonstrate these effects in the spectra of doubly 13C‐labeled solids.