Electron paramagnetic resonance (EPR) or electron spin resonance (ESR) is one of the most informative techniques for understanding the electronic structure of paramagnetic substances. EPR spectroscopy is particularly useful for studying (bio)chemical systems with strong local spin densities and their interactions with the environment. For these systems, EPR provides information on structure and dynamics and is widely used in chemistry, physics, and biology.
Saluki’ s DSP lock-in amplifier can be used to do the EPR measurement. EPR measurements are usually performed in continuous wave (cw) or pulsed (Pulse) mode. The cwEPR spectrometer (see figure) applies a magnetic field of about 0.35 T and measures microwave absorption (X-band) in the 9-10 GHz range. Typically, the microwaves are kept at a fixed frequency and sweep the magnetic field (from 0 mT – 700 mT for the X-band).
