electron paramagnetic resonance (redirected from Electron paramagnetic resonance spectroscopy)

electron paramagnetic resonance: see magnetic resonance.

---

electron spin resonance (ESR)

 or electron paramagnetic resonance (EPR)

Technique of spectroscopic analysis (see spectroscopy) used to identify paramagnetic substances (see paramagnetism) and investigate the nature of the bonding within molecules by identifying unpaired electrons and their interaction with their immediate surroundings. Unpaired electrons, because of their spin, behave like tiny magnets and can be lined up in an applied magnetic field; energy applied by alternating microwave radiation is absorbed when its frequency coincides with that of precession of the electron magnets in the sample. The graph or spectrum of radiation absorbed as the field changes gives information valuable in chemistry, biology, and medicine.

---

electron paramagnetic resonance [i′lek‚trän ¦par·ə·mag¦ned·ik ′rez·ən·əns]

(physics)

Magnetic resonance arising from the magnetic moment of unpaired electrons in a paramagnetic substance or in a paramagnetic center in a diamagnetic substance. Abbreviated EPR. Also known as electron spin resonance (ESR); paramagnetic resonance.