Double-Tuned Hopping-Coil Probe for Dynamic-Angle-Spinning NMR

A new design for a double-tuned dynamic-angle-spinning (DAS) probe that employs a RF coil wrapped directly around the stator is presented. The increased filling factor of this design and the smaller RF coil result in improved sensitivity and facilitate the incorporation of ‘H decoupling capabilities. Since the RF coil is reoriented with the spinning sample, the pulse lengths and sensitivity vary as the cosecant of the angle between the RF coil and the external magnetic field. However, this was not found to be a significant impediment to the usage of the probe. As a demonstration of the probes performance a ‘H-decoupled “B DAS spectrum of boric acid is presented. o 1992 Academic press, IX.