OPTICAL-ABSORPTION AND THERMOLUMINESCENCE STUDIES IN LIFMG,TI(TLD-100) SINGLE-CRYSTALS AS A FUNCTION OF IRRADIATION TEMPERATURE

Optical absorption (OA) and thermoluminescence (TL) studies are carrie d out in LiF:Mg,Ti(TLD-100) single crystals as a function of irradiati on temperature (T(irr)) from 77 to 523 K. While the variation in 310 n m OA and peak 5 (almost-equal-to 498 K) TL with T(irr) from 77 to 385 K is within +/-7%, the portion of 250 nm OA corresponding to peak 7 (a lmost-equal-to 573 K) and peak 7 TL increases drastically with T(irr) from 77 to 435 K. The latter result confirms that the OA of peak 7 cen tres occurs at 250 nm and that the radiolysis process is involved in t he creation of these defect centres. Due to thermal fading, the peak 7 TL and the above 250 nm OA decrease proportionally beyond T(irr) = 43 5 K confirming further the above correlation. A major outcome of this study is that two different defect centres - (i) centres giving rise t o peak 7 and (ii) isolated F centres not related to any of the TL peak s above room temperature - give rise to OA at the same or two position s close to 250 nm.