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RESEARCH PRODUCT

Magnetooptical studies of defects and recombination luminescence in LiBaF3

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Abstract Optically detected EPR investigations have been performed on the recombination luminescence (RL-EPR) of LiBaF3 crystal, X-irradiated at T=4.2 K . RL-EPR lines of VK- centres were found, as well as further lines of a defect with S= 1 2 and an axial g-tensor with its main axis along a [1 0 0] direction of the crystal. Measurements of the magnetic circular dichroism of the absorption (MCDA) have been performed on LiBaF3 crystals X-irradiated at two temperatures ( 4.2 K and RT). After irradiation at T=4.2 K , the main MCDA bands peak at 453 and 500 nm , but after irradiation at T=300 K , the main bands peak at 444 and 390 nm , there is a change of the sign between the peaks in both cases. The MCDA-detected EPR (MCDA-EPR) consists of one broad EPR line in both cases and belong to electron trap centres. Analysis of half-widths of MCDA-EPR lines showed that both defects should have g-tensors with their axes along the [1 0 0] direction. This symmetry has to be expected for F-type centres in LiBaF 3 crystals. The low-temperature electron centre has a more perturbed ground state as the RT centre.