Time resolved luminescence spectroscopy of alkaline earth oxides after pulsed electron beam irradiation. I. Spectra and thresholds of CaO and CaO:Mg

Abstract

Time resolved luminescence spectroscopy has been used to study the emissions occurring in CaO and CaO:Mg in the range 20 ns to 100 ms after irradiation with nanosecond duration pulses of electrons of energy between 0.2 and 3.0 MeV. An emission at 375 nm in pure CaO with a threshold energy of 0.29±0.2 MeV is attributed to processes resulting from the displacement of oxygen anions and the formation of F+ centers. A related emission in CaO:Mg is attributed to displacements involving oxygen anions and the formation of F+Mg centers. An emission at 560 nm observed in both CaO and CaO:Mg with a threshold energy ∼0.7 MeV is attributed to processes resulting from cation displacement. A surprising consequence of these observations is that the displacement energies of oxygen ions in the CaO lattice appear to be lower (∼50 eV for CaO and ∼35 eV in CaO:Mg) than that of the calcium cations (∼65 eV).