We are particularly interested in these nuclei because we are looking for hydrocarbons. Aligning the nuclear magnets Ordinarily, the north poles of nuclei point in whatever direction they want to point in. If no one tells them what to do, they will do what they want. The first step of an NMR measurement is to align the nuclear magnets with a strong magnetic field which we do by putting them in a large magnet. This makes them line up, with north poles of the nuclei pointing to the south pole of the magnet.
Magnetic nuclei are happy when they are aligned by a magnetic field.
They are in a comfortable state which physicists call equilibrium or low energy. It's a lot like a lazy kid just sitting on a playground swing, not going anywhere. Align the atomic nuclei in your hand. Simple, but not very spectacular. The second step of an NMR measurement is to get things moving.