Jahn-Teller distortion in the excited state of tellurium(IV) in Cs2MCl6 (M=Zr, Sn)

The luminescence spectra of the diluted systems Cs2ZrCl6:Te4+ and Cs2SnCl6:Te4+ are reported at liquid-helium and room temperature. The shape of the excitation spectrum of the Ten+ luminescence reveals a dynamic Jahn-Teller distortion in the excited state. At low temperatures the Te4+ emission shows a vibrational progression in the eg mode. The same vibrational mode is derived from the temperature dependence of the splitting of the A excitation band. Vibrational structure is also observed in the B band of the excitation spectrum of Cs2SnCl6:Te4+.