Quasioptical design for an EPR spectrometer based on a horizontal-bore superconducting solenoid

We describe a novel high-frequency electron paramagnetic resonance (HF-EPR) spectrometer design based on a horizontal-bore superconducting solenoid. Designs for components of a quasioptical HF-EPR spectrometer operating with a horizontal-bore 7.85 T solenoid are discussed. A rigid concentric tube construction permits precise placement and control of the optical elements in the magnet bore. A mechanically coupled, sliding optical table bearing the quasioptical bridge is another essential feature of the design. The horizontal configuration greatly improves optical alignment as well as physical access to the sample area compared to existing vertical-bore instruments. As a result, the minimum spin concentration that is detectable with an inexpensive room-temperature diode is comparable to the lowest values reported for aqueous samples in vertical-bore magnets using high-sensitivity detectors.