DOUBLE-QUANTUM HOMONUCLEAR ROTARY RESONANCE - EFFICIENT DIPOLAR RECOVERY IN MAGIC-ANGLE-SPINNING NUCLEAR-MAGNETIC-RESONANCE

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 omega(r) = 2 omega(1), where omega(r) is the sample rotation frequency and omega(1) 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 C-13 labeled L-alanine.