In May 2020, Dr. Alexey Kiryutin has installed an add-on to a 700 MHz NMR spectrometer (Avance III HD, Bruker). The setup allows one running NMR relaxation experiments in magnetic fields from 3 mT (30 Gauss) to 16.5 T. The operation principle is based on mechanical shuttling of the sample in the stray field of the superconducting NMR magnet, which smoothly decreases with the distance from the detection position. NMR spectra are always recorded at the sweet-spot of the NMR magnet. The mobile add-on allows one to use all currently available NMR probes without modification. The sample is fixed in a plastic carriage mounted on a gear rack. The rail is moved by a precise stepper motor, which is controlled directly by the pulse program of the NMR spectrometer. The positioning accuracy is 0.1 mm, the maximum travel distance is 90 cm, the minimal travel time between the most distant points is 300 ms. To our knowledge, this is the first fast field cycling setup based on a 700 MHz high-field NMR spectrometer. High resolution of the spectra allows one to obtain information on individual nuclei in even complex molecules. By measuring the nuclear magnetic relaxation dispersion one can obtain unique information about the mobility, namely, motional correlation time, of individual parts of the molecule. Examples of NMR spectra and the operation of the setup are presented in the video below.
https://doi.org/10.1039/C7CP08529J
https://doi.org/10.1002/mrc.4694 