Electron paramagnetic resonance

Electron paramagnetic resonance (EPR), also called electron spin resonance, detects transitions between electron spin states in a magnetic field. It chiefly probes substances containing unpaired electrons.

Electron spin: An intrinsic quantum property of electrons that gives them angular momentum and a magnetic moment. EPR detects transitions between electron spin states.
Spin trapping: A method that converts short-lived reactive radicals into longer-lived radical adducts for detection. EPR can identify transient radicals captured by spin traps.
Paramagnetism: A form of magnetism in which unpaired magnetic moments align weakly with an applied magnetic field. EPR-active samples are paramagnetic because they contain unpaired spins.
Nuclear magnetic resonance: A spectroscopic technique that detects transitions between nuclear spin states in a magnetic field. NMR probes nuclear spins, whereas EPR chiefly probes unpaired electron spins.
Zeeman effect: The splitting of energy levels when an external magnetic field interacts with magnetic moments. The applied field separates spin energy levels before resonance.
Electron spin labeling: The attachment of a paramagnetic probe to a molecule to study its structure or motion. EPR labels report molecular mobility and local environments.
Radical (chemistry): A chemical species with one or more unpaired electrons. Many molecular radicals produce characteristic EPR signals.
Electron nuclear double resonance: A technique combining electron and nuclear magnetic resonance to resolve interactions between electron and nuclear spins. ENDOR extends EPR by selectively probing coupled nuclear transitions.
Electron g-factor: A dimensionless factor relating a particle's magnetic moment to its angular momentum. Its value helps determine the field at which a spin resonates.
Dynamic nuclear polarization: A method that transfers electron spin polarization to nuclei to enhance nuclear magnetic resonance signals. EPR supplies the electron spins used to boost nuclear polarization.

Linked from 19 pages