A two-axis goniometer for sensitivity enhancement in single-crystal nuclear magnetic resonance spectroscopy

Abstract

The construction of a single-crystal nuclear magnetic resonance (NMR) probe with a new two-axis geometry for the goniometer has improved the sensitivity of the NMR response from small crystals. This allows studies of the smallest crystals used so far in single-crystal NMR. The goniometer of the probe uses only two different mountings of the crystal, and the rotation axis of the goniometer is tilted 45° with respect to the direction of the magnetic field. By moving the goniometer outside the radio frequency coil, the filling factor and the probe sensitivity increase. The improved sensitivity for the probe is illustrated by the P-{H1}31 cross-polarization spectrum of a 0.088 mm3 crystal of (NH4)2HPO4 and a Rb87 single-pulse spectrum of a 0.048 mm3 crystal of RbZn2(HPO4)PO4. Moreover, the capability to determine precise parameters for the solid-state NMR interactions using the new probe is demonstrated by Na23 and Rb87 single-crystal studies of NaNO3 and RbClO4.