Design And Manufacturing Of A Magic Angle Spinning Unit For Solid-state Nuclear Magnetic Resonance Probe

With the development of solid-state nuclear magnetic technology,more and more scientific research units use the magic angle spinning technology to carry out nuclear magnetic resonance research on solid samples.Magic angle spinning(MAS)technology is an important method to improve the resolution of solid nuclear magnetic resonance signals and narrow the line width of the spectrum.This method forces the sample to follow the MAS rotor to rotate rapidly in the direction of 54.73560°with the direction of the main magnetic field through the MAS unit.And the anisotropic interaction between the cores of the solid sample is eliminated or weakened.As a vital part of the solid-state nuclear magnetic resonance magic angle spinning(MAS)probe,the MAS unit is a necessary guarantee for the high-speed rotation under the magic angle of solid samples,which determines the scope and performance of the MAS probe.For example,the HR-MAS unit can be used to apply MAS probes to experiments with extremely high resolution requirements.Therefore,it is important to research the MAS unit for improving the resolution of solid-state NMR signals.However,the lack of research on MAS units in the country has long been subject to the monopoly of foreign markets,which has seriously restricted the development of domestic solid-state nuclear magnetic resonance.In this paper,the research on the design and fabrication of MAS units is carried out for the requirements of domestic solid-state NMR routine experiments on MAS units.The main work of the thesis is as follows:(1)Through in-depth study of MAS unit,this paper summarizes the key factors that need to be paid attention to when designing MAS unit.After considering factors such as qualification,design difficulty,assembly and post-maintenance difficulty,the design scheme of MAS unit is selected.Based on this,a conventional 4 mm MAS unit was designed,and the MAS rotor and the radial aerostatic bearing were designed in detail.(2)The fluid-solid coupling simulation of the MAS unit is carried out.The gas flow pressure distribution of the radial hydrostatic bearing and the stress and strain of the rotor are analyzed.At the same time,the modal simulation of the rotor is carried out to determine the various vibrations of the rotor.Type and critical speed point.The rationality of MAS unit design is verified by simulation.(3)The MAS unit was fabricated and tested for speed.The test results show that the self-made MAS rotor is operated normally at 14 kHz with the self-made MAS stator.The self-made MAS unit was mounted on an existing solid-state nuclear magnetic resonance probe,and NMR sampling was performed on a 400M nuclear magnetic resonance spectrometer.The 'H NMR signal of the adamantane sample was collected at 4 kHz and 12.5 kHz.Fully explain that the self-made 4 mm MAS unit can meet the requirements of conventional solid-state nuclear magnetic resonance experiments.