Magnetic circular dichroism and the assignment of charge transfer transitions in tetrahalide complexes

Abstract

Magnetic circular dichroism (MCD) spectra are reported for the charge transfer transitions in a large number of tetrahalide complexes of first transition series ions. Spectra of all the compounds have been obtained from solutions at room temperature and also, for CoI₄ ^2– and NiI₄ ^2–, from evaporated films and doped crystals at various temperatures down to liquid helium temperature. Assignments are discussed in terms of models based on Russell-Saunders, first-order spin-orbit or j,j-coupling, depending on the size of the halogen spin-orbit coupling constant.