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We have used flash luminescence stimulation and photoinduced emission methods to study deep impurity states of AgCl(I) microcrystals with adsorbed organic cationic and anionic dye molecules. We have observed that when these molecules interact with the crystal, charge transfer occurs simultaneously from different orbitals and the transfer occurs differently from each orbital: some orbitals of the molecule pick up a negative charge, others at the same time give up a negative charge. We hypothesize that the type of transfer is determined by the overall charge.Introduction. The phenomenon of spectral sensitization of the photoelectric effect, the initial step in many photoelectronic processes in crystals (external photoelectronic emission, photoconductivity, the photochemical process, anti-Stokes luminescence, frequency multiplying, etc.), is widely used in practice [1][2][3][4]. A special role is played by sensitization by organic dyes, due to the considerable diversity of their spectral characteristics, making it possible to design light energy detectors and converters having selective and conversely nonselective properties in the visible and near IR regions of the spectrum [1,4].In [5], for the example of methylene blue molecules adsorbed on the surface of AgCl(I) microcrystals, it is shown that they are bound to the crystal mainly by several active centers (the dimethylamino group and the sulfur atom of the heterocycle) via OH groups. Accordingly, a direct optical transition of electrons in the molecule to the conduction band is unlikely. After lengthy study, a large amount of information has been accumulated and several mechanisms for this phenomenon have been developed. But it is not completely clear how the mechanism operates in each specific case. There has been a lack of deep understanding of the reason for the high quantum yield of spectral sensitization, as high as unity in a number of cases. This is especially connected with two problems: determination of the relative position of the energy levels for the sensitizer and the crystal, and identification of the nature of their interaction. Therefore it is important to develop new methods for solving these problems and using such methods for measurements.Experiment. The most sensitive method for investigation of deep impurity states, making it possible to make measurements in the case of a millionth (~10 -8 to 10

We have observed a significant increase in the intensity with anti-Stokes excitation of recombination luminescence in AgCl(I) microcrystals sensitized by methylene blue molecules in the presence of silver nanoparticles.Introduction. In recent decades, considerable research has been conducted to study the effect of metallic bodies on the optical properties of molecules and atoms. In particular, luminescence of organic molecules increases by an order of magnitude near silver and gold microparticles and nanoparticles [1,2]. An increase in the luminescence intensity has also been observed with anti-Stokes luminescence excitation for some molecules near silver particles of size 100-150 nm [3]. The most pronounced enhancement was apparent in surface-enhanced Raman scattering of light (SERS) by molecules adsorbed on the rough surface of precious metals and near small metallic particles [4]. In this case, the intensity of the Raman lines increased by many orders of magnitude. These facts concerning the enhancing effect of metallic particles on emission of local quantum objects (atoms, molecules) are explained by resonance of electronic transitions in them with collective oscillations of confined electrons [5]. The question arises concerning whether metallic particles might have the same effect on recombination luminescence in crystal phosphors. Such an effect can be directly studied in silver halides, which on the one hand luminesce well at low temperatures and on the other hand decompose when exposed to UV radiation, with separation of colloidal silver particles [6]. In this case, the silver particles prove to be in direct contact with the rest of the crystal. However, in this case, the luminescence intensity decreases (the "luminescence fatigue" effect) [7]. This is determined by the appearance of a strong channel for nonradiative recombination of electrons and holes. Furthermore, the presence of metallic particles leads to shielding and re-absorption effects [8]. Therefore in this work, we investigated the effect of metallic particles on recombination luminescence for anti-Stokes luminescence excitation in the crystals. In this case, all the effects reducing the luminescence intensity can be taken into account by comparing the luminescence of the crystals in the presence of and in the absence of the metallic particles.We synthesized a fine-grained emulsion of silver chloride microcrystals with small iodine impurity in gelatin. We know that luminescence of these microcrystals occurs via the Scho .. n-Klassen recombination mechanism [9]. The weight percent of gelatin relative to the water was 5%. This emulsion was divided into several portions. Then 5 mL of each portion of the emulsion was poured on a 9 × 6 cm glass plate, after which the samples were dried under standard conditions. In all cases, the thickness of the layers was 37 ± 2 μm. All these layers were exposed at room temperature to light from a 60 W incandescent lamp at a distance of 30 cm for 5 min, which led to formation of silver nanoparticles in the microc...