Abstract: An MAS probe is disclosed for obtaining a substantial improvement in signal to noise (S/N) in triple-resonance high-resolution (HR) magic-angle-spinning (MAS) NMR of samples near room temperature (RT) in high-field magnets where the magnet's RT shim bore is greater than 60 mm. All critical circuit components, including the sample coils, are located along with the spinner assembly in a thermally insulated cold zone pressurized with helium gas. The spinner assembly attaches to a sealed, curved, rotor-loading tube to permit automatic sample change, and it is surrounded by a partially insulated jacket cooled with a cryogenic fluid, generally nitrogen gas. The MAS probe is also compatible with magic angle gradients, variable temperature operation, field locking, and commonly available closed-cycle cold fingers.

Abstract: An NMR probe contains a metallic dewar for use in a high field magnet, the dewar characterized as having a major fraction of its inner wall made from an alloy whose weight composition includes at least 70% copper, less than 20% zinc, less than 10% nickel, less than 8% Cr, less than 4% Pb, less than 0.15% iron, less than 0.15% cobalt, and at least 3% from the set comprised of tin, silicon, aluminum, and chromium, and said inner wall further characterized as being plated with a pure metal on at least one surface.

Abstract: An improved axial gas bearing for a gas-driven NMR MAS sample rotor is disclosed that utilizes inward flow with a low rotational component over a rotor conical end. A conical flow region is formed between the rotor conical end and a conical stator bearing surface such that the included angle defining the stator surface is not less than the included angle defining the rotor conical end. Gas is injected radially inward with a significant axial rearward component from a number of small holes at high velocity from the periphery into the conical flow region. Compared to the radial velocity components, the tangential flow components of the injected gas are small and preferably opposed to the direction of the rotor rotation.