Commercial gigahertz-class NMR magnets

Abstract

Nuclear Magnetic Resonance (NMR) spectroscopy is a wide-spread analytical technique which is used in a large range of different fields, such as quality control, food analysis, material science and structural biology. In the widest sense, NMR is an analytical technique to determine the structure of molecules. At the time of writing this manuscript, commercial NMR spectrometers with a proton resonance frequency ≥ 900 MHz are only available from Bruker. In 2019, Bruker installed the first 1.1 GHz (25.8 T) NMR spectrometer at the St. Jude Children Research Hospital in Memphis, Tennessee, followed by the installation of the first 1.2 GHz (28.2 T) NMR spectrometer at the University of Florence in Italy in 2020. These were the first commercial NMR spectrometers operating at magnetic fields in excess of what can be achieved with conventional low temperature superconductors, and which depend on high temperature superconductors to generate the required magnetic field. In this paper, the requirements on commercial NMR magnets are discussed and the history of high-field NMR magnets is reviewed. Bruker’s R&D program for 1.1 and 1.2 GHz NMR magnets and spectrometers will be described, and some of the key properties of these first commercial NMR magnets with high-temperature superconductors are reported.

Primary Structure of Glycans by NMR Spectroscopy

“…Further increase of the magnetic field strength corresponding to a 1 H frequency of 900 MHz was promoted by cooling the NMR coil using subcooled superfluid helium at a temperature of ∼ 2 K. At a 1 H frequency of 900 MHz, the dispersion of resonances increases significantly, which is highly beneficial in structural studies of complex oligosaccharides, although some spectral overlap of resonances still occurs for closely similar structural elements in oligosaccharides originating from polysaccharides with repeating units (Figure ). A decade later, the first 1 GHz NMR spectrometer made its appearance . However, above this magnetic field of ∼ 23.5 T, the critical current density for Nb 3 Sn-based alloys decreases steeply and superconductivity will disappear.…”

“…A decade later, the first 1 GHz NMR spectrometer made its appearance. 468 However, above this magnetic field of ∼ 23.5 T, the critical current density for Nb 3 Sn-based alloys decreases steeply and superconductivity will disappear. To reach even higher magnetic fields with ultrahigh field NMR spectrometers operating at 1.1 and 1.2 GHz hybrid designs have been developed, whereby high-temperature superconductors (HTS) using "copper-oxides" are utilized in the inner section of the solenoid magnet and LTS in the outer portion of the magnet.…”

The effect of methyl group rotation on 1H–1H solid-state NMR spin-diffusion spectra

“…The gain in resolution of 1 H-detected spectra is related to a decrease in homogeneous line broadening caused by the strong proton-proton dipolar coupling network. 8 Combining fast MAS with very high static magnetic-field strengths, such as the recently commercially available 28.2 T superconducting NMR magnets, 9 is expected to further decrease homogeneous linewidths, as illustrated by first examples. 10,11 It has been recognized early on that spin diffusion (SD) provides an effective source for transferring polarization between dipolar-coupled nuclei 12 and is, thus, of high importance for employing NMR in structure-determination techniques.…”

First Validation of Robust REBCO Insert Concept on a Large 20-Pancake Prototype Reaching Up to 25 T

“…It consists in an 11 T BSCCO insert with a 14 T LTS outsert. It was the first user magnet operating above 23 T, and is still to date the only conduction-cooled magnet operating above that limit, even though several other user or commercial magnets operate now above 25 T or are expected to do so [2][3][4]. Since then research activities were conducted at HFLSM together with Toshiba to develop the technology for REBCO insert for upgrading this magnet to reach 30 T while retaining the ease of use offered by cryogen-free operation of an insulated magnet [5,6].…”