Optical detection of a hydrogen complex responsible for the F phosphorescence in thermochemically reduced MgO crystals.

Abstract

A hydrogen complex denoted as [${\mathrm{H}}_{\mathrm{x}}$${\mathrm{}}^{\mathrm{\ensuremath{-}}}$${]}^{0}$ has been detected using optical-absorption techniques. The local mode of the hydrogen in the anion sublattice resonates at 1037 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ and a broad absorption peaking at 400 nm characterizes the electronic transition of this complex. It is shown to be the predominant electron trap involved in the photoconversion process of F\ensuremath{\rightarrow}${F}^{+}$ centers. It is metastable at room temperature, giving rise to the F phosphorescence (the thermoluminescence which peaks at 260 K). We further demonstrate that this complex is not the defect identified previously as an ${\mathrm{H}}^{2\mathrm{\ensuremath{-}}}$ ion by electron paramagnetic resonance at low temperature.