Rapid-Scan Electron Paramagnetic Resonance

In rapid-scan EPR, the magnetic field is scanned through resonance in a time that is short relative to relaxation times. The signal is recorded with a quadrature mixer at the resonance frequency. Relaxation-time-dependent effects on the trailing edge of the signal are removed by deconvolution, giving the absorption spectrum. For a wide range of samples, the signal-to-noise ratio obtained by rapid scan is substantially higher than for conventional continuous wave spectroscopy because the full spectrum is detected on each pass through resonance, higher microwave power can be used without signal saturation, and coherent averaging decreases noise.