This report exposes some experimental results relating the mechanism of spectral sensitization of photosensitive microsystems “Core CaF2 + dye + shell AgBr”. The studies were aimed at expanding their spectral sensitivity into the infrared (IR) region and reducing the effects of the dye self-desensitization.
In this work, a hologram optical element is proposed for optical-electronic angle measuring devices and sighting systems, which is a combination of four three-dimensional diffraction gratings registered in the volume of a photosensitive medium. The method of measuring the angular displacement and sighting of objects is based on the properties of changing the intensity of the information light signal of volumetric hologram optical elements, in accordance with the modulating effect of the object under study. The sensitivity of the proposed device for the measurement range of ±150 ang. min was 5 ang.s. In sighting mode with a range of 3 ang. min. the sensitivity was 0.1 ang. s.
Volume holograms have high angular and spectral selectivity and diffraction efficiency (DE) up to 100%. Media for recording volumetric holograms must have high resolution, high photosensitivity, low noise level, write stability to storage and reading, reversible recording capability, and the material itself must be cheap and easy to manufacture and use. In the proposed work, for the registration of three-dimensional holograms, a photosensitive emulsion containing heterophase microsystems "nuclei of homogeneous CaF2 particles with a size of ~ 40 nm - an AgBr shell with a thickness of ~ 5 nm" is proposed.
We study the processes of interaction between molecules and H-aggregates of a dye adsorbed at the surface of AgBr and AgBrI emulsion microcrystals (EMC). Methods of the low-temperature (T = 4.2 K) luminescence enable to associate the “self-desensitization” with the mechanism conditioned by the interaction of Н- and J-aggregates of the dye with its molecules, which results in the decay of the spectral sensitivity of emulsions employing organic dyes. Methods of low temperature (T = 77 K) luminescence show the interaction of the first excited state of the Н-aggregates with the triplet state of the molecular dye, which indicates the process of the excited Н-aggregates’ energy dissipation through the triplet state of its molecules.
In the study of low-temperature (T = 77 K) luminescence of anionic, cationic and neutral-typel dyes adsorbed on the surface of AgHal microcrystals in molecular, H- and J-aggregated states, electron-hole processes are revealed that are responsible for the anti-Stokes anomalously slowed-down fluorescence and phosphorescence of the molecular dye upon its j-aggregate excitation. Based on the results obtained, a luminescent technique is proposed that enables to control the interactions processes between molecular and polymolecular forms of dyes of the three charge states. These processes are responsible for the "self-desensitization", and ways to reduce the negative impact of the "self-desensitization" effects are considered.
We have studied spectral sensitization with anionic dyes of holographic microsystems “core – silver halide shell” (CSHS), cores of which can be either nonsilver or silver halide compounds. Conditions under which dye sensitizers, being adsorbed on cores, remain under silver halide shells after their growing are considered. Comparison of results of sensitometric and low-temperature (Т = 77 K) luminescent measurements have shown that these conditions are determined by the charge state of cations of microsystem cores. If the shell contains the same univalent component in its composition as the core does, as in the case in which the core is a silver halide compound, the anionic dye is displaced to the outer surface of the shell. If the core contains a divalent cationic component, as in the case in which the core is a nonsilver compound, the dye remains under the silver halide shell; i.e., it is overgrown by the shell. We have shown that the charge state of core cations affects the character of the core interaction with anionic dyes, which ensures differences in the spectral sensitization of CSHS microsystems, as well as differences in the dye photoexcitation relaxation in them. We have found that supersensitization of AgBr microcrystals sensitized by infrachromatic dye affects the interaction between the dye aggregates and the surface silver ions, which induces modification of the holographic microsystems’ spectral sensitivity range.
In this article we formalize and consider the path-planning problem on the weighted graph with prizes (PCPP - prize collecting path-planning). It is generalized travel salesman problem on graph with prizes. We give the formal statement of the PCPP problem and prove that it is NP-hard. We developed the algorihtm to resolve the PCPP problem exactly if graph is a tree and proposed several heuristics based on this algorithm to resolve the problem in common case.
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