[en] The electron excitations and processes of their radiation relaxation in pure and alloyed by Ce³⁺ ions crystals of lanthanum beryllate by excitation through synchrotron radiation of the X-ray and vacuum ultraviolet (VUV)-ranges are studied by the methods of optical and luminescent VUV spectrometry with time resolution (2-40 eV). Manifestations of the valent zone excitons in the reflection spectra are absent. However fast (τ = 1.7 ns) and slow (μs-range) channels, corresponding to two possible types of auto-localized excitons (ALE), are determined at T = 10 K in the radiative relaxation of proper electron excitations. The slow channel corresponds to the ALE radiation, formed through the recombination method, and the fast one corresponds to the radiation of relaxed metastable excitons from the ALE state. The effect of the electron excitations on the account of generating the secondary electron-hole pairs as a result of inelastic scattering of both hot photoelectrons and hot photo-holes is displayed in the area of energies above 14 eV