Submillimetre EPR spectrometer

A wide-band submillimetre EPR spectrometer is described. A set of tunable backward wave oscillators and quasioptic lens system enables one to operate in the frequency region 79–535 GHz. The sample is placed in a magnetic field of up to 1 T at 4.2 K. The spectrometer is intended for the investigation of EPR spectra of rare-earth ions in solids with zero field splittings of the ground states near the frequency of operation and/or electron systems with ag-factor exceeding 5. The spectrometer’s capabilities are demonstrated with an investigation of the EPR spectra of Dy²⁺ and Dy³⁺ ions in CaF₂. As a result the exact value of the zero field splitting between the ground Γ₈ quartet and the first exited Γ₇ doublet of Dy³⁺ in CaF₂, Δ=257±0.5 GHz, has been measured directly.