Broadband Millimeter Wave Paramagnetic Resonance Spectrometer

Abstract

A flexible magnetic resonancespectrometer is described. Its transmission type microwave structure can be usedbetween 50 and 150 kMc. A modified Varian magnet gives a field of 28 000 gauss, homogeneous to 3 gauss over atypical sample area. A Dewar vessel fits into the 3 4 -in. magnet gap and permits cooling of the sample below theλ point of helium. The millimeter waves are generated by backward wave oscillators, and harmonic conversion isused for the frequency measurement and control. A modification of the spectrometer makes possible the directmeasurement of line width and frequency of zero-field lines.