Electronic Structure of the Centers in ZnS

A model of the common sulfide luminescent centers is proposed. The mutual perturbation of crystal eigenstates and transition-metal (activator) $d$ eigenstates is assumed to give rise to the excited and unexcited eigenstates of the center. For substitutional ${\mathrm{Cu}}^{+}\left(d^{10}\right)$ in zincblende, zeroth order crystal field theory predicts that two sets of occupied center ground-state levels ($T_2$ and $E$) originating from $d^{10}$ will exist. Additional level splittings result from (a) the spin-orbit effect, and (b) axial crystal field splittings in wurtzite. Experiments on visible and infrared, excitation and emission, are used to make tentative assignments of magnitude of level splittings.