Hydroxyl ions and the 200−nm absorption band in Mg− and Ti−doped thermoluminescent LiF single crystals

Abstract
A study of the distribution of the optical absorption coefficient of the 200−nm band in Mg− and Ti−doped LiF single−crystal boules, grown from monocrystalline starting materials of varying purity, indicates that this absorption band is due to titanium−hydroxyl complexes. The measurements of ionic conductivity and infrared absorption on the starting materials and in doped crystals indicate that each titanium ion probably interacts with several hydroxyl ions to form these complexes, and that the association of hydroxyl ions is stronger with titanium ions than with magnesium ions. Since earlier work has shown that the 200−nm band is involved in the thermoluminescent recombination process, it is indicated that hydroxide impurities may be essential constituents in dosimetry grade LiF.