OPTICAL-ABSORPTION AND LUMINESCENCE IN LITHIUM-FLUORIDE TLD-100

The isothermal decay at 25 degree C of the optical absorption bands in irradiated LiF TLD-100 single crystals has been compared with the decay, under the same conditions, of thermoluminescence (TL) and dielectric loss. The decay of the 380-nm band can be described by a third-order process suggesting that this band is directly related to free Mg-vacancy dipoles, which cluster during aging to form trimers. When compared with recent measurements which indicate that the TL peaks 2 and 3 are not related to the Mg dipoles, the present results infer that the 380-nm band is not directly related to these TL peaks either, in contrast to earlier conclusions. This assertion receives some support from pulse annealing measurements and from x-ray-induced luminescence spectra. A comparison of the data with recent thermoluminescence spectra measurements leads to the suggestion that TL peak 2 is caused by Mg dipole/Ti complexes, and that TL peak 5 is caused by Mg trimer/Ti complexes.