Radial-Field Sidebands in MAS

Field modulation effects induced by sample spinning: application to high-resolution magic angle spinning NMR

“…In this region, the intensity of the radial and axial component of the field become comparable and the direction of b ra 1 is roughly along the normal of the ring. This situation is similar to the one described by Goldman and co-workers [104,105].…”

Magnetization transfer magic-angle-spinning z-spectroscopy of excised tissues

“…If the solenoid RF coil produces an ideal B 1 field, perfectly parallel to and concentric with the axis of sample rotation, then MAS would impose no time-modulations and no sidebands would arise. But as noted by Hoult and Richards [49] and examined in further detail by Tekely, Engelke and coworkers [50,51], non-idealities in the coil can also generate spatially-dependent B 1 components that will become frequency modulated by ±x r , ±2x r offsets upon imposing the MAS. These non-idealities will in general stem from a solenoid that is not infinite and perfectly symmetric along its main Z-axis.…”

Using a cross-coil to reduce RF heating by an order of magnitude in triple-resonance multinuclear MAS at high fields

“…In some cases, B 1 inhomogeneities transverse to the spinner axis can have significant effects [24]. Generally speaking, these inhomogeneities give rise to amplitude and phase modulations of B 1 (as well as of the detected NMR signal [25]) as a sample volume element orbits about the spinner axis. These modulations tend to be small, but as they are synchronous with the sample rotation, they can lead to unintended spin dynamics when the applied RF pulse sequence is also rotor-synchronous, as is the case for most recoupling sequences.…”