Jahn-Teller effect in the luminescence spectra of ZnS and ZnSe

The infrared emission spectra of ZnS:(Formula presented) and ZnSe:(Formula presented) are reported examining temperature dependence. The unusually rich spectra are theoretically explained by assuming a vibronic coupling due to ε modes. A diagonalization of the Hamiltonian matrix is performed using wave functions constructed in the Born-Oppenheimer limit. The Jahn-Teller energy is the only adjustable parameter. When this parameter is about 80 (Formula presented) for ZnS:(Formula presented) and 65 (Formula presented) for ZnSe:(Formula presented) good agreement between theory and experiment is found and the main features of the spectra for both systems are explained. The frequencies of the coupling modes are taken close to the TA(L) modes.