Radial-field sidebands in MAS

The existence of sidebands at +/-v(r) in MAS spectra due to the radial component of the RF field at the edges of the coil is described theoretically and illustrated experimentally. The height of the radial-field sidebands does not depend on the spinning speed and may contribute significantly to the intensity of -1 spinning sideband of MAS modulated internal interactions for a sample placed in a rotor of length exceeding the solenoid coil or a small volume sample placed at the edge of the coil.