For some crystals with ionic-covalent bonds (AgHal, CdS, ZnS) under the action of UV- radiation large light fluxes, a decrease of steady luminescence is revealed that is stimulated by the formation of absorbed small atomic clusters playing the part of electrons and recombination centers. The formation of these clusters is explained by the availability of a photosimulated surface migration of absorbed silver, zinc, and cadmium atoms and ions. The electronic and acceptor properties of the absorbed atoms and clusters are studied, and the activation energies of the particles' photostimulated migration are measured. This work suggests the mechanism and the kinetic model of this migration.
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