QUASI-OPTICAL CW MM-WAVE ELECTRON-SPIN-RESONANCE SPECTROMETER

We describe a novel cw millimeter-wave electron spin resonance (ESR) s pectrometer designed to operate in the frequency range of 80-200 GHz a nd in the temperature range of 2.5-300 K, which may be easily scaled t o higher frequencies. The spectrometer uses a bimodal reflection cavit y coupled to a circular corrugated guide and uses Gaussian quasi-optic s for most of the front-end signal processing. This technique has very low insertion loss and allows a number of sophisticated measurement t echniques to be employed including induction operation, which signific antly reduces the effect of microphonics and stray reflections. A numb er of examples are given illustrating the sensitivity of the instrumen t and the advantages of using ESR at high fields. (C) 1998 American In stitute of Physics. [S0034-6748(98)00311-6].