THE ORIGIN OF THE F+ CENTER RADIOLUMINESCENCE IN SAPPHIRE

Electron irradiation of sapphire produces primarily F centres, in mark ed contrast with neutron and ion irradiations where both F and F+ cent res are produced. However, radioluminescence studies during electron i rradiation indicate bands associated with both F and F+ centres. These emission bands show a complex dependence on dose rate and temperature . A systematic study of the radioluminescence spectra as a function of these two parameters together with optical absorption measurements in dicate that the ionization of F centres is the cause of the F+ centre radioluminescence. A model describing the way the F+ emission occurs i s proposed and compared with the results obtained. (C) 1997 Elsevier S cience B.V.