In EPR spectroscopy, a sample is exposed to a constant magnetic field and electromagnetic radiation, usually in the microwave range. Unpaired electrons have a magnetic moment due to their spin, and under the influence of the magnetic field, these spins can align either parallel or antiparallel to the field. When the energy of the microwave radiation matches the energy difference between these spin states, resonance occurs, and absorption is detected. This absorption is plotted as an EPR spectrum, which provides information about the electronic environment of the unpaired electrons.
