HIGH-RESOLUTION NEAR-INFRARED LUMINESCENCE OF MANGANESE(V) IN TETRAHEDRAL OXO COORDINATION

Manganese (V)-doped crystals of Ba5(PO4)3Cl (apatite structure) and Ca2VO4Cl (spodiosite structure) exhibit highly resolved photoluminescence in the near-infrared. It is assigned to intraconfigurational 1E --> 3A2 (T(d) notation) transitions, and the vibrational sideband structure is interpreted in terms of bending and stretching vibrations of the (MnO4)3- entity. In lightly doped samples of the apatite compound, both the intensity and the lifetime of the luminescence (tau-10K = 0.56 ms) remain essentially constant up to room temperature, whereas in the spodiosite compound, the luminescence lifetime (tau-10K = 0.41 ms) drops by an order of magnitude between 10 K and room temperature.