VUV spectroscopy of OH--doped LiF crystals

Abstract

Absorption, emission and excitation spectra of LiF single crystals doped with LiOH have been measured in the UV and VUV regions of the spectrum. An absorption band at 137 nm has been identified as the UV absorption of OH/sup /ons, while bands at 172, 200 and 280 nm are assigned to defects caused by other impurities accidentally contained in the crystals. Only one emission band at 409 nm, assigned to O2- centres, has been observed at all temperatures under excitation in the various absorptions belonging to different defects. As a consequence, an energy transfer mechanism between different centres is suggested. A weak luminescence at 255 nm, excited only in the fundamental absorption, is proposed as an intrinsic emission of LiF.