Abstract
ABSTRACT New luminescence emission bands have been found in the infra-red region at 1-8 μ for cadmium sulphide phosphors. The emission is analogous to that recently found for zinc sulphide phosphors at 1.6μ A systematic study has been made of the infra-red emission in a large number of zinc sulphide, zinc-cadmium sulphide and cadmium sulphide phosphors. It is excited by raising electrons from, the valence band of the phosphor lattice into the ground states of the normal luminescence centres. The latter are either empty in the normal state, or must first be emptied by suitable excitation giving rise to the well-known visible and near visible luminescence of these phosphors. The return of electrons to the valence band gives rise to the infra-red emission. The excitation spectra for the infra-red emission correspond to the quenching spectra for the visible luminescence and for the photoconduction of the above phosphors. A new infra-red stimulation band of the visible emission of ZnS has been found at about 2.55μ, which may well correspond to the single thermal glow peak of these phosphors.
Published Version
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