Correlation of optical absorption and thermoluminescence curves for single crystals of magnesium oxide

Optical absorption and thermoluminescence measurements on untreated crystals of magnesium oxide have shown that the crystals can be divided into two groups. X irradiation of the crystals induces an optical absorption peak at 2.3 ev in group I crystals and at 2.3 and 3.0 ev in group II crystals. Thermoluminescence curves, recorded after x irradiation of the crystals at room temperature, show a peak at 410°K for group I crystals and at 410 and 520°K for group II crystals. By an optical bleaching method the 2.3 and 3.0 ev absorption peaks are shown to be linked respectively with the 410 and 520°K thermoluminescence peaks. The ratio of the optical and thermal activation energies of the trapped charge carriers is shown to be 3.3 for these magnesium oxide peaks.