Investigation of the EPR g factors and defect structure for the Cu2+-VNa center in the X-irradiated NaCl: Cu+ crystal

The g factors of a tetragonally-compressed Cu2+ center in NaCl: Cu+ crystal X-irradiated at room temperature are calculated from the high-order perturbation formulas based on the two-mechanism model. In the model, the contribution to g factors from both crystal-field (CF) and charge-transfer (CT) mechanisms are included. The calculations are based on the defect model that the tetragonally-compressed Cu2+center is assigned to the Cu2+ ion (which is caused by Cu+ ion (at the Na+ site) irradiated by X-ray) associated with a nearest Na+ ion vacancy VNa along C4 axis due to charge compensation. From the calculations, the g factors g|| and g⊥ are explained and the defect structure (charactering by the displacement ΔZ of the Cl- ion intervening in Cu2+ and VNa) of the Cu2+ (or Cu2+-VNa) center is obtained. The results are discussed.