Abstract
After irradiation in AgCl crystals doped with Cu and Se or S, respectively, an ESR spectrum of a Cu2+ ion is observed the octahedral chlorine environment of which is distorted by a Se2− or S2− ion. The centre has [100] tetragonal symmetry and a essentially |3 z2r2 > ground state. The superhyperfine structure in AgCl: 77Se, Cu indicates a strong interaction with one selenium nucleus. If σ‐bonding is assumed the magnitude of the covalency between the Cu2+ and the Se2− ion can be estimated: the hole spends about 20% of its time in a pz state of the Se2−. From the existence of this covalent bonding in the paramagnetic complex follows that the spin‐orbit coupling is more reduced in [Cu2+ Se2−] than in [Cu2+ S2−].