Time-resolved luminescent VUV spectroscopy of F- and F+-centres in single BeO crystals

The time-resolved photoluminescence spectra in the energy region of 2.0–6.0 eV, as well as the excitation spectra (4.0–35.0 eV) and the decay kinetics of luminescence (the time region of 0.2–500 ns) were studied for F- and F+-centres in beryllium oxide crystals at T=10 and 295 K using selective vacuum ultraviolet excitation. The synchrotron radiation from the storage ring DORIS was used. The aim of the present work was to investigate and compare the stoichiometric BeO crystals with anion-imperfection samples. F- and F+-centres performed the role a of luminescent probe in a crystal lattice. The efficiency of energy transfer to F- and F+-centres was investigated on this basis. The role of the electron–hole and exciton mechanisms of energy transfer in BeO crystals and their dependence on temperature were determined. The photoconversion F+→F was found using time-resolved spectroscopy methods. A comparison of emission properties of F- and F+-centres in BeO and α-Al2O3 crystals was made.