ESR fundamentals

Electron paramagnetic resonance (EPR or ESR) is an important branch of magnetic resonance which is usually carried out by sweeping the magnetic field at a microwave frequency of about 9 GHz. The ESR spectrum is described by a function of two variables, viz. magnetic field and frequency and the implications of field sweeping are discussed. Increasingly, pulsed methods, especially electron spin echo envelope modulation and its variants, are becoming more important in all areas of ESR applications.