3. Detection modes

The technique used initially was continuous-wave NMR. The B ₁ field is then of very low intensity. Resonance is obtained by slowly varying B ₀ at a constant B ₁ frequency or conversely the B ₁ frequency at a fixed B ₀ field.

Pulse NMR is the current technique for obtaining all the information contained in the overall magnetization of a sample, even when dealing with low-sensitivity nuclei of low natural abundance, such as ¹³ C (1.108%), ¹⁵ N (0.37%), or low gyromagnetic ratio, such as ¹⁰³ Rh