Use of a Parametric Amplifier in Electron Spin Resonance Spectrometer Design

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Abstract
An electron spin resonance spectrometer, employing a commercially available parametric amplifier as an RF amplifier, was tested to determine the reduction in instrument noise figure brought about by the parametric amplifier. The observed noise figure of 15 dB for the spectrometer was reduced to 41 dB by a parametric amplifier that exhibited a noise figure of 3.2 dB by independent tests. The related improvements in sensitivity for this instrument and for other spectrometer configurations are discussed and found to lie in the range of two to ten fold, depending upon the original configuration and the noise figure of the parametric amplifier. The stability and ease of operation of the parametric amplifier suggest that it may serve as a useful accessory in those instances where a spectrometer is used at the limit of its capabilities, as is often the case with studies involving aqueous biological materials and other dilute or lossy paramagnetic samples.