ESR An introduction

Electron spin resonance (ESR) spectroscopy has been used for over 60 years to study a variety of paramagnetic species. ESR otherwise known as Electron paramagnetic resonance (EPR) is a spectroscopic technique in studies of systems with unpaired electron spin (i.e. paramagnetic body). This is essence deals with transition between Zeeman levels which may occur whenever a paramagnetic substance is placed in a magnetic field and at the sometime exposed to electromagnetic radiation.