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Electron Spin Resonance (ESR/EPR) Spectroscopy

Electron spin resonance (ESR) or electron paramagnetic resonance spectroscopy (EPR) is a sophisticated spectroscopic technique that detects free radicals or inorganic complexes in chemical and biological systems. Generally, these radicals are unstable, but when they are first reacted with spin-trapping reagents, they can be trapped and stabilized. On the other hand, with use of a spin-labeling reagent, the molecules without radicals can also be measured with ESR/EPR.