THE (4)T(1)(F)-](4)A(2)(F) LUMINESCENCE OF THE CO-2+(D7) IMPURITY CENTER IN ZINC SELENIDE CRYSTALS

The 4T1 (F) --> 4A2(F) transition of Co2+ (d7) ions in ZnSe is detected by its emission at T almost-equal-to 4 K. The no-phonon line at nu-BAR = 5558 cm-1 is demonstrated to coincide with the inverse absorption transition. The luminescence shows medium coupling to ZnSe lattice vibrations. An exponential decay with a time constant tau = 100-mu-s is recorded. A rich fine-structure is displayed by the 4T1 (P) <-- 4A2(F) absorption studied for comparison. Qualitatively, it can be described by spin-orbit and Jahn-Teller interaction. Finally, the properties of two additional emission bands present in the 4200 to 5600 cm-1 region are illustrated, one of them dominated by a no-phonon line at 5471 cm-1. Capture of a hole by a neutral donor is discussed as a possible interpretation of a broad luminescence band peaking near 4600 cm-1.