Structural and optical properties of low energy electrons irradiated KCl:LiF multilayer films

The optical behaviour of point defects created by low energy electron beams is studied in multilayer KCI:LiF films, grown by thermal evaporation onto amorphous substrates at constant temperatures ranging from 30 to 350 degrees C. The surface morphology of the samples was observed by the atomic force microscopy (AFM) technique, Large concentration of F and F-aggregate centres has been produced by 3-7 keV electron irradiation both in KCI and LiF layers which constitute the film. By pumping our films with appropriate Ar+ laser lines, we measured, for the first time, the luminescence in the near infrared region due to F-2 and F-3 centres in KCl and the typical emission of F-2 and F-3(+) centres in LiF in the visible region.