Z(Ag-) centres in NaCl:(Ag++Ca2+) crystals

After direct electrolytical colouring or electron irradiation followed by illumination in the F centres absorption band of the NaCl:(Ag++Ca2+) crystal samples, a new centre has been observed denoted by us with Z(Ag–). The 300 nm absorption band of this centre is close to the well known Aga– absorption band from 275 nm. The photoluminescence band of the Z(Ag–) centre is observed at 600 nm compared to the 440 nm photoluminescence band of Aga–. The photoluminescence band position depends on the nature of the divalent cation impurity peaking at 560 nm for Sr2+ codoped samples. The obtained results prove that the Z(Ag–) centre is an Ag– ion perturbed by the divalent cation. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)