Annealing effects and optical absorption of thermoluminescent lithium fluoride

The changes in the optical absorption of thermoluminescent dosimetry grade lithium fluoride observed as functions of various pre-irradiation and post- irradiation heat treatments have been related to the thermoluminescent properties of the material. Correlations have been made of the 3.23 eV absorption band to the glow peaks at 115 degrees C and 160 degrees C, and the 3.99 eV absorption band to the peaks at 195 degrees C and 210 degrees C. Determinations of the trap depths and frequency factors yield figures in reasonable agreement with those previously obtained from thermoluminescent data. A model for the trap distribution and movement is presented which is consistent with the observations and with the variation of thermoluminescent sensitivity reported previously.