COLOUIR CENTRES IN OXIDESOrigin of the luminescence excited in the F absorption band in MgO
Domain: Physics
The F and F+ centres are known to have almost coincident absorption bands at 250 nm in MgO. Exciting this absorption band results in two luminescence bands at 400 nm and 520 nm. The former has been attributed for a long time to the F+ luminescence and the latter to the F luminescence. Optically detected magnetic resonance, stress effects and lifetime measurements invalidate this last statement. It will be shown that the 520 nm luminescence originates in a recombination process, similar to donor-acceptor recombination in semi-conductors. The recombining entities are the F+ and the F- centres. The observation of the 400 nm and (or) the 520 nm bands is very sensitive to the wavelength of the exciting light, showing a complicated photoconversion process between F and F+ centres.
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The F and F+ centres are known to have almost coincident absorption bands at 250 nm in MgO. Exciting this absorption band results in two luminescence bands at 400 nm and 520 nm. The former has been attributed for a long time to the F+ luminescence and the latter to the F luminescence. Optically detected magnetic resonance, stress effects and lifetime measurements invalidate this last statement. It will be shown that the 520 nm luminescence originates in a recombination process, similar to donor-acceptor recombination in semi-conductors. The recombining entities are the F+ and the F- centres. The observation of the 400 nm and (or) the 520 nm bands is very sensitive to the wavelength of the exciting light, showing a complicated photoconversion process between F and F+ centres.
Article published online by
EDP Sciences
and available at
http://dx.doi.org/10.1051/jphyscol:19806139
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Publié le :
29/06/2012
Langue :
Français
Nombre de pages :
2
Type de la publication :
Rapports et thèses
Thème :
Savoirs >
Science de la nature
Source :
Journal de Physique Colloques
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