Electron Spin Resonance : ESR theory

Principle

The resonant absorption of microwaves by magnetic moments of unpaired electrons is measured in the presence of a static magnetic field(H). The splitting between the two energy states(Ms=±1/2) is proportional to the magnetic field. Absorption of energy causes a transition from the lower energy to the higher energy state. A spectrum is obtained by sweeping the magnetic field. Defects and chemical species can be evaluated from the ESR spectrum.