kärnmagnetresonans

Kärnmagnetresonans, often abbreviated as KMR or NMR from its English counterpart Nuclear Magnetic Resonance, is a spectroscopic technique used to study the structure and dynamics of molecules. It relies on the magnetic properties of atomic nuclei, specifically those with a non-zero nuclear spin. When placed in a strong external magnetic field, these nuclei align themselves either with or against the field, creating distinct energy states.

A radiofrequency pulse is then applied to excite these nuclei, causing them to transition to a higher energy state. As the nuclei return to their lower energy state, they emit electromagnetic radiation at a specific frequency, known as the resonance frequency. This emitted signal is detected and analyzed to provide information about the molecule's chemical environment. Different nuclei within the same molecule will experience slightly different magnetic fields due to the surrounding electron clouds, leading to variations in their resonance frequencies. These variations, called chemical shifts, are characteristic of the particular atom and its molecular surroundings. KMR is a powerful non-destructive analytical tool employed across various scientific disciplines including chemistry, biology, medicine, and materials science.