Optical absorption in LiF:Mg, Ti and its relationship to thermoluminescence and thermoluminescence dose response

The optical absorption (OA) spectrum of LiF:Mg, Ti has been investigated by optical bleaching and I_m-T_stop pulsed annealing in steps of 3-4°C over the temperature range from 100°C to 300°C. In agreement with previous investigations, the 5.45 eV OA band is identified as a likely candidate for the recombination stage competitor responsible for composite peak 5 supralinearity. An additional OA band at 5.7 eV is also identified as a possible recombination stage competitor. First-order kinetic analysis yields an activation energy of 0.8 ± 0.13 eV for the 4.0 eV band usually associated with peak 5, an energy which is similar in value to the binding energy of the Mg-Li_vac trimer believed to form the peak 5 trapping structure. Dose response measurements result in dose filling constants of β_TC = 0.9±0.1 × 10^-3 Gy^-1 and β_CC = 3.8±0.8 × 10^-4 Gy^-1 for the 4.0 and 5.45 eV OA bands, respectively. These dose filling constants deduced from OA measurements can be used in the framework of the unified interaction model (UNIM) to study the dose response supralinearity of composite dosimetric peak 5.