Nuclear magnetic resonance spectroscopy.

Abstract

The introduction to this section discusses how spraying things at materials can be a method for learning about their properties. Nuclear magnetic resonance (NMR) spectroscopy works in a similar, but subtly different way — it induces the materials themselves to do the spraying. NMR is a phenomenon that occurs when the nuclei of atoms in a strong magnetic field resonate with small oscillations in the near field (the portion of the magnetic field close to them) generated with radiofrequency (RF) pulses (Figure 4.13.1). The resonance causes nuclei to give off electromagnetic radiation, which carries information about the properties of those nuclei — in particular their magnetic moment, which can identify elements and give hints about how atoms are arrayed in a crystal or molecule. This information can be invaluable for determining molecular and crystal structure, monitoring chemical reactions or biological processes as they unfold, analyzing the purity of samples, and for applications like imaging. NMR has therefore become a widespread technique for investigating physical, chemical, and biological materials…