Infrared luminescence of ZnSe : Cr crystals

Abstract At 4 K, the emission of ZnSe : Cr crystals around 4500 cm −1 displays a zero-phonon doublet and vibronic structures. The radiative transition is 5 A 1 ( 5 E) → 5 B 2 ( 5 T 2 ) at substitutional Cr 2+ whose symmetry is reduced from T d to D 2d by the static Jahn-Teller-effect. The excitation spectrum of this band indicates band-to-band transitions, photoionization of centres and transitions to Cr 2+ excited states. These latter are fitted in the Tanabe-Sugano approximation. Additional structured emission bands near 6000 and 10 000 cm −1 are investigated.