A SHUNT FABRY-PEROT RESONATOR FOR HIGH-FREQUENCY ELECTRON-SPIN-RESONANCE UTILIZING A VARIABLE COUPLING SCHEME

We report on the performance of a Fabry-Perot resonator for far-infrar ed electron spin resonance (FIR-ESR) at 250 GHz designed to accommodat e a thin, disk-shaped sample that must rest with its flat surface perp endicular to the incident FIR beam. This geometry minimizes dielectric losses, making it possible to obtain FIR-ESR spectra of aqueous or lo ssy samples with a macroscopic ordering, at canonical values of the di rector tilt of 0 degrees and 90 degrees. The resonator also utilizes a n adjustable interferometer to achieve variable coupling in the FIR re gime. (C) 1998 American Institute of Physics.