Double-quantum homonuclear rotary resonance: Efficient dipolar recovery in magic-angle spinning nuclear magnetic resonance

TLDR

The authors present an efficient method to recover homonuclear dipole–dipole interactions in magic‑angle spinning NMR, enabling double‑quantum filtering and measurement of these interactions. They achieve this by implementing double‑quantum homonuclear rotary resonance (2Q‑HORROR), satisfying the condition ωr = 2ω1 between the rotation and nutation frequencies. The method yields orientation‑independent spin dynamics, suppresses chemical‑shift effects to zeroth order, and is demonstrated on singly and doubly 13C‑labeled L‑alanine.

Abstract

We describe an efficient method for the recovery of homonuclear dipole–dipole interactions in magic-angle spinning NMR. Double-quantum homonuclear rotary resonance (2Q-HORROR) is established by fulfilling the condition ωr=2ω1, where ωr is the sample rotation frequency and ω1 is the nutation frequency around an applied resonant radio frequency (rf) field. This resonance can be used for double-quantum filtering and measurement of homonuclear dipolar interactions in the presence of magic-angle spinning. The spin dynamics depend only weakly on crystallite orientation allowing good performance for powder samples. Chemical shift effects are suppressed to zeroth order. The method is demonstrated for singly and doubly 13C labeled L-alanine.