NUCLEAR MAGNETIC RESONANCE (NMR)
So lets start from a very basic. Each atom consists of a nucleus and that is very specific to each atom (no two atoms can have same nuclear arrangement). This nucleus is always in spinning motion like a top. This motion of nucleus generate magnetic field because nucleus(contains proton) possesses electric charge and each moving charged species generate the magnetic field . Difference between spinning and precessional motion:- Spinning Precession Simple nucleus is always spinning on its axis. But when this nucleus comes under the external magnetic field, it shows precessional motion as with spinning . this is spinning as well as precessing This external magnetic field causes the nucleus to adopt two orientations (like bar magnet oriented with earth's magnetic field)one is higher in energy(opposed) and other is in lower one(aligned).