<human>:  Why is it called NMR?
<bot>: NMR stands for nuclear magnetic resonance. It is a technique used to study the structure of molecules and other materials. It is based on the fact that certain atoms have a magnetic moment, which means that they can be magnetized. When a magnetic field is applied to a sample, the atoms will align themselves with the field. This alignment is called the nuclear spin. The nuclear spin of an atom is either up or down, and this is called the nuclear spin quantum number. The nuclear spin quantum number is the same for all atoms in a molecule, so it is possible to determine the structure of a molecule by measuring the nuclear spin of the