PHOTOLUMINESCENCE OF LIFNAF FILMS AT ROOM-TEMPERATURE

In this paper we present the results of the photoluminescence spectra of multilayer LiF:NaF films colored by low energy (3 keV) electron beams. We show that dielectric multilayered films can be used in the design of new materials with optical properties that cannot be matched by bulk materials

PHOTOLUMINESCENCE OF LIF CRYSTAL COLORED BY A FOCUSED ELECTRON-BEAM

The absorption, emission and excitation optical spectra of F2+ and F3+ color centers generated in LiF through low energy (30 keV) electron beam irradiation were measured at room temperature by pumping with an Ar+ laser the resulting thin colored layer. A quenching of the emission intensity of the F3+ centers versus the pump power was observed, with characteristics similar to bulk colored crystals. The analysis of the photoemission spectra showed a new band, which has been discovered previously also in bulk crystals colored and treated in different ways. The possibility of applications of the colored ribbon for miniaturized laser devices is commented

NaF films: Growth properties and electron beam induced defects

Polycrystalline NaF films were grown by e-beam assisted physical evaporation on amorphous silica substrates kept, during film growth, at constant temperatures ranging from 40 degrees C to 400 degrees C. The structural characterization of the films was performed by X-ray diffraction and by scanning electron microscopy. Irradiating the films with a 15 keV electron beam induced the formation of F and F-aggregate colour centres stable at room temperature. Absorption and photoemission measurements were performed and indicated a dependence of coloration on the deposition conditions

F-AGGREGATE CENTERS IN KCL FILMS

The optical behaviour of colour centres is studied in thin films of KCI obtained by thermal evaporation onto amorphous substrates. Deposition conditions are optimized in order to minimize chemical and thermal effects on films. Concentration of colour centres even higher than in bulk crystals can be induced by low energy electron irradiation. Thermal bleaching of F centres is observed at room temperature and its kinetics, deduced from absorption measurements, consists of two exponential processes with very different time constants. Luminescence is obtained for the first time from aggregate colour centres in KCl films, and typical emissions of F-2, F-3, F-4 defects (but not of F centres because of concentration quenching) are revealed