Abstract
For pt. I see abstr. A7013 of 1972. Expressions for the g-values and hyperfine structure parameters of Cu2+ ions in tetragonally distorted tetrahedral sites are derived by including the effects of covalency, 4p mixing and the dynamic Jahn-Teller effect. The results are applied to Cu:Cs2ZnCl4 where agreement with EPR and optical data is obtained by taking the Jahn-Teller reduction factor K(T1) approximately 0.65, covalent bonding approximately 18% and 4p mixing approximately 4%.