PHOTOLUMINESCENCE OF NEUTRON-IRRADIATED LiF SINGLE CRYSTALS

In 1980, a single LiF crystal was irradiated by thermal neutrons up to the exposition dose 10(19) n/cm(2) at the Salaspils nuclear reactor. The crystal has been kept at room temperature for 29 years. Samples in size of 5x4x1 mm(3) were cut from the crystal and some of them annealed at 920 K for 30 min. To study photoluminescence, measurements with a confocal laser scanning microscope Leica TCS SP5 were performed, during which 3D-defects of size of similar to 1 mu m(3) were revealed. Photoluminescence was observed in the red spectral region with the peak of similar to 655 nm when excited with an argon laser (lambda = 458 nm).