Paramagnetic Resonance Spectrum of Cr+++ in Emerald

Survey articles by Bleaney and Stevens 1 and Bowers and Owens 2 list paramagnetic resonance data for crystals containing ions of the transition groups. A careful study of these tabulated data reveals t h a t most of the crystals studied are hvdrated or contain several magnetically nonequivalent ions and, therefore, discourages the use of many of these crystals in a practical three-level solid-state maser (3LSSM). The present study was undertaken with a view to investigating crystals doped with paramagnetic ions which possess good chemical stability and which might be expected to have energy-level schemes suitable for extending the design of solid-state masers to higher microwave frequencies. In this article, paramagnetic resonance spectra of emerald (Cr-doped beryl) are reported. The large zero field splitting observed for the C r + + + ion in this crystal might suggest emerald as a possible material for use in the design of solid-state masers for high microwave-frequency applications. I I . CRYSTAL S T R U C T U R E AND S P I N H A M I L T O N I A N O F E M E R A L D