NMR spectroscopy is a technique that uses radiofrequency energy and magnetic fields to study atomic nuclei and their spin properties. It works by applying a magnetic field to nuclei with an odd number of protons or neutrons, causing them to precess. Radiofrequency energy is then applied, which can be absorbed by the nuclei to excite them to a higher energy state. When the radiofrequency is removed, the nuclei return to the lower energy state and emit radiofrequency signals that are measured. Fourier transform NMR (FT-NMR) uses mathematical operations to convert the complex time-domain signals into a frequency-domain spectrum, improving sensitivity and resolution compared to non-FT NMR.