Jahn-Teller effect and the luminescence spectra of (formula presented) in ZnS and ZnSe

A dynamical Jahn-Teller effect has been proposed to interpret the fine structure of the luminescence spectra of (formula presented) impurities in ZnS and ZnSe. The ground (formula presented) term of the impurity is split by the crystal field into three multiplets. The spin-orbit and the spin-spin interactions are taken into account as well as a linear Jahn-Teller coupling with a trigonal phonon mode, both on the ground (formula presented) multiplet and on the excited (formula presented) multiplet. The Lanczos-recursion procedure with a proper choice of the initial state is followed to calculate the vibronic states. A comparison with experimental energies and intensities indicates that a dynamical Jahn-Teller effect plays an important role to explain the fine structure of the luminescence spectra of (formula presented) and (formula presented) In the latter, the temperature effects present in the spectra are also accounted for by the resulting energy-level scheme.