Behavior of TL glowcurves for natural quartz samples from liquid-nitrogen temperature up to room temperature

On Z-cut slices of a natural quartz crystal, color center images and thermoluminescence (above room temperature) color images were compared together with the distributions of Al and OH group (and molecular H2O) impurities in infrared spectra. Dense color center (CC) parts correspond to low impurity contents and intense blue thermoluminescence (BTL) parts, whereas colorless (CL) parts corresponded to high-impurity and weak BTL. On the other hand, CL parts showed strong BTL emissions below -100∘C, while CC parts gave apparently weak BTL. An annealing treatment (at 1050∘C for 30 h) of CL parts brought a great decrease of BTL emissions below -100∘C, probably related to expelling of OH groups and molecular H2O from the CC parts. Based on a comparison between BTL glowcurves of CC and CL parts and the ESR signal intensity of Al-hole centers in CL parts below room temperature, it was suggested that hydrogen radicals and some reactive species (radiolysis products from OH groups and molecular H2O) erased Al-hole centers, leading a decrease of BTL emissions above room temperature. Another major impurity, i.e. Li, was suggested to contribute to BTL emissions about -40∘C.