Transverse Zeeman effect for ions in uniaxial crystals

Abstract

The theory of the Zeeman effect for ions in crystals at sites of uniaxial symmetry has been developed for intra-configuration transitions with the external magnetic field H perpendicular to the crystal axis c . Variations in the axial optical spectrum that occur when the crystal is rotated about c are described in terms of the types A and B of the upper and lower states involved in the transition. Large intensity changes can occur for ions at sites of D 4 , C 4v or D 2d symmetry for those transitions that appear only in the σ spectrum. Analogous variations can only take place for D 6 , C 6v and D 3h in those cases where H is sufficiently large to mix neighbouring crystal-field states. Other uniaxial point groups are considered as cases of approximate symmetry. The theory is developed with particular reference to U 5+ in zircon, to CoCs 3 Cl 5 , and to the rare-earth ethylsulphates.