Chemical testing electron spin resonance spectroscopy

Electron paramagnetic resonance (EPR), also called electron spin resonance (ESR) spectroscopy, is used to determine the electron spin for atoms with unpaired electrons. Most atoms have electrons that are paired together, because this makes them more stable. But radicals do not have spin pairs, and they can be tested using this method. Free radicals are often short-lived species, but they are also very important in the outcome of a chemical reaction. So when you can track their progress, you can better understand the mechanisms of chemical reactions. 

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