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.