The Electronic Structure of the Alkaline‐Earth Oxides. V. Peculiarities of the Hole‐Trapping in NaF and MgO

Abstract

Calculations are made for clusters simulating the Vk‐center in NaF and a hypothetic self‐trapped hole in MgO within the embedded cluster approach. The “non‐ionic” charge configuration of MgO, described earlier, is analysed as a possible cause of the absence of the hole self‐trapping manifestations in the oxide according to the mechanism known for NaF. Due to the delocalization of oxygen 2p‐states the hole orbital is oriented, in contrast to NaF, perpendicularly to the 2‐anion quasi‐molecule axis, while the hole state itself lies close to the top of the potential barrier bonding this state.

Thermoluminescence and Phosphorescence of VUV‐ and X‐Irradiated CaO Monocrystals at Low Temperatures

“…There are two emission bands at 4.6 and ~2 . 6 eV, but by contrast with the X-ray excited luminescence spectrum, the relative intensity of the 4.6 eV emission band is much higher. As 2.6 eV emission has an excitation band at ~4 .…”

“…As 2.6 eV emission has an excitation band at ~4 . 6 eV [12], the weight of the 4.6 eV emission in the phosphorescence is still larger. on cation vacancies (V centers).…”

“…In [5], the calculated "non-ionic" charge configuration of alkaline-earth oxides (AEO) was considered as a possible cause for the absence of the self-trapping of holes and excitons. On the other hand, such a charge configuration may be regarded as a result of the unusual barrier-like shape of the potential for valence electrons in these AEO [6], that may account also for the observed reversed order of lines [7] within the exciton doublets of MgO and ') Riia 142, EE-2400 Tartu, Estonia.…”