Sensitivity enhancement in ESR/ENDOR spectrometers by use of microwave amplifiers.

The introduction of a low-noise microwave preamplifier in a homodyne ESR spectrometer can increase the signal-to-noise ratio by more than a factor of 10 at low modulation frequencies, and makes it superior to a superheterodyne spectrometer. The performance of this new arrangement has been compared to that of a normal homodyne spectrometer.