Institut für Technische und Makromolekulare Chemie, RWTH Aachen University, Aachen, Germany.
J Magn Reson. 2019 Sep;306:27-35. doi: 10.1016/j.jmr.2019.07.030. Epub 2019 Jul 9.
NMR started at low field. Important discoveries like the first observation of NMR in condensed matter, the spin echo, NMR for chemical analysis, Fourier NMR spectroscopy, 2D NMR spectroscopy and magnetic resonance imaging happened at field strengths considered low today. With time the footprint of the NMR instruments at these field strengths shrunk from the laboratory floor to the tabletop. The first commercial tabletop NMR instruments were compact relaxometers for food analysis followed by mobile relaxometers for materials testing and oil-well exploration culminating in tabletop spectrometers for chemical analysis, capable of performing nearly the whole methodical portfolio of today's high-field instruments. The increasing sensitivity afforded by the lower noise of modern electronics and the unfolding richness of hyperpolarization scenarios along with detection schemes alternative to nuclear induction enable NMR at ultra-low field strengths down to zero applied field, where spin-spin couplings in local fields dominate the residual Zeeman interaction. Miniaturization and cost-reduction of NMR instruments outline current development goals along with the development of smart-phone-like apps to conduct standard NMR analyses.
NMR 始于低场。在今天看来，当时被认为处于低场强的条件下，却诞生了许多重要的发现，如凝聚态物质中首次观察到的 NMR、自旋回波、用于化学分析的 NMR、傅里叶变换 NMR 光谱学、二维 NMR 光谱学和磁共振成像。随着时间的推移，这些场强下的 NMR 仪器的足迹从实验室的地面缩小到了桌面。第一批商用桌面 NMR 仪器是紧凑的用于食品分析的弛豫计，随后是用于材料测试和油井勘探的移动弛豫计，最终发展成为用于化学分析的桌面光谱仪，能够执行当今高场仪器几乎所有的方法学组合。现代电子设备的低噪声提供了更高的灵敏度，同时伴随着极化方案的丰富性不断展开，以及除核感应之外的检测方案，使得 NMR 能够在超低场强下（低至零施加场）运行，在该场强下，局部场中的自旋-自旋耦合主导残余塞曼相互作用。NMR 仪器的小型化和成本降低是当前的发展目标，同时还开发了类似于智能手机的应用程序，用于进行标准的 NMR 分析。
