[H2O-]Z CENTERS IN LIF-OH- CRYSTALS

Electron-irradiated LiF:OH- crystals at -30 degrees C exhibited a new centre absorbing in the region of F-z centre at 380 nm. The kinetics o f defect formation and destruction suggest that both OH- and Mg++ impu rities must be present in the host to propitiate its production. The i somorphism between the observed excitation spectra of this centre with the absorption of H2O- centres in alkali chlorides and bromides cryst als, suggested that it must be of the same nature, i.e. a 'wet F-z cen tre', although more stable due to the intrinsic Mg++ effects. (C) 1997 Elsevier Science Ltd. All rights reserved.