0000000000594150
AUTHOR
J. E. Muñoz Santiuste
Photoconversion and dynamic hole recycling process in anion vacancies in neutron-irradiated MgO crystals
Optical spectroscopy and theory demonstrate that photon excitation of the positively charged anion vacancies (F{sup +} centers) at 5.0 eV in neutron-irradiated MgO crystals releases holes that are subsequently trapped at {ital V}-type centers, which are cation vacancies charge compensated by impurities, such as Al{sup 3+}, F{sup {minus}}, and OH{sup {minus}} ions. The concentration of trapped-hole centers was found to exceed that of available anion vacancies. The disproportionately large amount of holes produced is attributed to a dynamic recycling process, by which the F{sup +} center serves to release a hole to the {ital V}-type centers and subsequently trap a hole from an Fe{sup 3+} ion.…
Photoconversion of F+ centers in neutron-irradiated MgO
Abstract In neutron-irradiated MgO crystals, experiments and theory demonstrate that photon excitation of the positively charged anion vacancies (F+ centers) at 5.0 eV releases holes that are subsequently trapped at V-type centers, which are cation vacancies charge-compensated by impurities, such as Al3+, F−, and OH− ions. A photoconversion mechanism occurs very likely via electron transfer to F+ centers from the quasi-local states which are induced in the valence band. INDO quantum chemical simulations of F+ centers confirmed the appearance of two induced quasi-local states located at 1.2 and 2.0 eV below the top of the valence band.