The topic is the radiative and nonradiative decay of electronic excitations with the creation of radiation defects in LiF. A luminescence band with a peak at 3.45 eV is observed in the x-ray luminescence spectrum at 4.2 K; it may be assigned to the luminescence of a self-localized exciton. In LiF-Na, additional luminescence bands with peaks at 2.0 and 2.4 eV are observed; these may be attributed to the luminescence of electron excitations localized around the Na' ion. The formation of Frenkel defects at 4.2 K in LiF and LiF-Na is discussed.