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In the present, photoluminescence of δ-KIO3 HIO3 crystals has been studied for the first time in the temperature range of 4.2-77K. It was shown experimentally that at T=4.2 K the edge of self-absorption band is located near 295 nm. In the luminescence spectra of the title crystal, two bands are found which differ in their spectral position and lifetime. The short-wave luminescence band centered at 367.5 nm. This band appears only in the csae of the crystal excitation by the light with the wavelength that does not fall in the region of self-absorption of the crystal, eg λexc = 340 nm. When the temperature increases from 4.2 to 34 K, the intensity of this band falls down almost to the background value, whereas the position of its maximum remains practically unchanged. The long-wave luminscence band of the δ-KIO3 HIO3 crystal with peak position at 410-420 nm and the lifetime of about 1 s is attributed to phosphorescence. This spectrum appears only in the case of excitation within the region of self-absorption of the crystal, eg λ3xc = 275 nm. On the basis of experimental data analysis, the assumption has been made that the short-wave band originates from the emission of excitons located at the defects of the crystal structure, and the long-wave band is related to radiation decay of autolocated bihalide excitons. Possible photoprocesses in the title crystal caused by light absorption of different wavelength are discussed.
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