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Based on the investigation of the spectra of two-photon excited luminescence of powder zinc sulfide electroluminophors, their electroluminescence spectra measured under different conditions at different stages of degradation, and also the data known from the literature dealing with the study of the microstructure of ZnS:Cu crystals, a conclusion has been drawn that the centers of green and blue luminescence are nonuniformly distributed over the luminophor grains. It is presumed that close by the surface of the grains, near the “second phase–zinc–sulfide” interface (the regions of energy barriers responsible for impact multiplication of charge carriers in prebreakdown electroluminescence) the centers of green luminescence predominate, while the blue luminescence centers are located at the periphery of the barriers, in deeper regions of the crystals.

Abstract: Two-photon-excited luminescence (TEL) spectra have been recorded in the blue (400–500 nm) and near-ultraviolet (300–400 nm) ranges for diamond particles with 4 nm average size, which were obtained by detonation synthesis from explosives. The observed TEL bands are attributed, by comparing the obtained spectra with the impurity luminescence spectra in large diamond crystals, to N2 and N3 defects associated with the presence of nitrogen impurities in diamond. The TEL spectra presented are found to have certain distinguishing features: short-wavelength shift of the maximum and changes in the shape and width of the spectral bands for ultradispersed diamond compared with the spectrum in bulk crystals.