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Luminescence of O2 -and (O2-- F+) color centers in KBr single crystals

FouziaZehani

The optical properties of KBr single crystals elaborated by the Czochralski method are studied. The excitation of samples with 270 nm shows a series of emission lines between 500-800 nm, which are assigned to the electronic transitions from the lowest vibrational level  ï‚¢  0 of the excited state 2ðu to vibrational levels  ï‚¢ of the ground state 2ðg of O2 - centers. However, the emission spectra of samples excited with 360 nm after annealing, present an intense emission band centered at 710 nm and a weak large band between 400-500 nm, formed by three peaks each one situated at 415, 440 and 468 nm. The measure of excitation spectra show that these emission bands are due to (O2-- F+) centers.