LUMINESCENT PROPERTIES OF SURFACE RADIATION-INDUCED DEFECTS IN LITHIUM FLUORIDE
Uminescence excitation and emission spectra were recorded for surface radiation defects in lithium fluoride at temperatures of 77 and 293 K. A distinguishing feature of the excitation spectrum is the presence of three bands rather slightly differing in their intensities. All these bands were demonstrated to belong to the same type of defects. The peak positions and widths of absorption and luminescence bands were evaluated for these defects. The l uminescence decay time was measured. It is found that all measured characteristics of the surface defects differ from those of previously known radiati on defects formed in the bulk of crystals. The luminescence of the surface defects in the ensemble of nanocrystals with various orientations was found to be no n- polari z ed. A number of anion vacancies comprising the surface defects were deduced from the results of polari z ation measurement s. It is demonstrated that radiation scattering distort s the intensity ratios for the luminescence excitation bands located in different spectral regions.