arXiv subjects

Sergei V. Naydenov

Publications and source records attributed to Sergei V. Naydenov.

3 recordsLinked to original sources

arXiv2025

Binary $ZnSe:Fe^{2+}$ and ternary $ZnMgSe:Fe^{2+}$ optical crystals for mid-IR applications

In this study, binary $ZnSe:Fe^{2+}$ crystals and ternary $Zn_{1-x}Mg_{x}Se:Fe^{2+}$ crystals $(0 < x < 0.6)$ were grown by the vertical Bridgman method in graphite crucibles under high argon pressure. A comparative characterization of the structural, energetic, and optical parameters of the obtained crystals was performed. Theoretical explanations of the observed experimental characteristics, including the specific red-shift of the absorption and emission spectra with increasing solid-solution concentration, are provided. These results could be useful for the development of new laser media based on simple and complex AIIBVI crystals and for targeted engineering of their optical properties.

physics.optics↗

arXiv2011

Dispersions of multi-walled carbon nanotubes in liquid crystals: new challenges to molecular theories of anisotropic soft matter

Aggregation of carbon nanotubes dispersed in nematic liquid crystalline medium is discussed. A model is proposed, which assumes that the aggregates consist of a "skeleton" formed by stochastically arranged nanotubes and a "shell" ("coat") of incorporated and adjacent nematic molecules. The aggregates of this type can be considered as large quasi-macroscopic particles in the nematic matrix. The resulting composite system represents a new type of complex molecular liquids involving self-organization of particles in anisotropic medium. Many essential features and implications of the theoretical model (e.g., effects of concentration of the nanotubes, their aspect ratio and orientational order parameter on the size and fractal dimensionality of the aggregates formed, as well as on the rate of aggregation) are in good agreement with experimental data obtained by various physical methods.

cond-mat.mes-hall↗

arXiv2006

Multi-Energy Radiography Against Terrorism. Theory and Experiments

Multi-energy radiography is a new direction in non-destructive testing. Its specific feature is separate detection of penetrating radiation in several energy channels. Multi-energy radiography allows quantitative determination of the atomic composition of objects. This is its principal advantage over conventional radiography. In particular, dual-energy radiography allows determination of the effective atomic number of a material with an accuracy of up to 80-90%. Development of three-energy radiography and radiography of higher multiplicity makes it possible to further improve the reconstruction of an objects chemical composition. This presents the possibility, for example, of detection of explosives and other illegal objects in luggage with a reliability approaching 100%. These developments can find application not only in anti-terrorist activities, but also in areas such as industrial testing and nuclear medicine.

physics.ins-det↗