Rotary resonance recoupling of dipolar interactions in solid-state nuclear magnetic resonance spectroscopy

TLDR

The technique is expected to enable measurement of internuclear distances in disordered materials such as polycrystalline solids, polymers, and surfaces. The study introduces a new resonance effect in solid‑state NMR. It combines magic‑angle spinning with selective irradiation at the Larmor frequency of one spin species. When irradiation intensity matches spin nutation to sample rotation, the heteronuclear dipolar interaction is selectively reintroduced, allowing small dipolar couplings to be measured despite large shielding anisotropies.

Abstract

A new resonance effect in solid-state nuclear magnetic resonance (NMR) is described. The effect involves a combination of magic-angle sample rotation with irradiation of a heteronuclear spin system at the Larmor frequency of one of the spin species. If the irradiation intensity is such as to establish a match between spin nutation and sample rotation, it is shown that the heteronuclear dipolar spin interaction is selectively reintroduced into the spectrum. This allows small dipolar coupling constants to be measured in the presence of large shielding anisotropies. Applications are anticipated for determination of internuclear distances in materials lacking long-range order, such as polycrystalline materials, polymers, and surfaces.