Photoinduced thermoluminescence in corundum

By means of measurements of X-ray-induced luminescence, photoluminescence, optical absorption, and time-resolved spectroscopy, it is shown that all nominally pure corundum crystals examined by us obtain chromium and titanium as an impurity. The photoinduced thermoluminescence of nominally pure corundum single crystals is due to the release of electrons from F centers and Ti3+ ions and holes from Cr3+ ions during illumination of the crystals with light. The limiting energies of photons that arouse a TL response are 5.5, 4.9, and 3.4 eV, respectively. (author)