JAHN-TELLER EFFECT IN THE LUMINESCENCE SPECTRA OF ZNS-V-V+( AND ZNSE)

The infrared emission spectra of ZnS:V+ and ZnSe:V+ are reported exami ning temperature dependence. The unusually rich spectra are theoretica lly explained by assuming a vibronic coupling due to epsilon modes. A diagonalization of the Hamiltonian matrix is performed using wave func tions constructed in the Born-Oppenheimer limit. The Jahn-Teller energ y is the only adjustable parameter. When this parameter is about 80 cm (-1) for ZnS:V+ and 65 cm(-1) for ZnSe:V+ good agreement between theor y and experiment is found and the main features of the spectra for bot h systems are explained. The frequencies of the coupling modes are tak en close to the TA(L) modes.