A precision paramagnetic resonance spectrometer

Abstract

An instrument is described for the accurate comparison in the same magnetic field of the frequency of electronic magnetic resonance absorption, particularly in gaseous materials, with the frequency of proton resonance absorption. Details are given of (1) the production of a homogeneous magnetic field, which can be stabilized at any value between 1 and 11 kG; (2) the production and measurement of the radio-frequencies used for the observation of proton resonance in this field; (3) the supply and measurement of a stable microwave frequency in the region of 9000 to 10 000 Mc/s; (4) the sensitive detection of paramagnetic resonance absorption at this frequency using 115 kc/s magnetic field modulation. The precision of the measurements is about three parts per million; it is limited mainly by the homogeneity of the magnetic field, and the measurement of the proton resonance frequency.