The structure of CdS nanoparticles

CdS nanoparticles in the high-pressure polyethylene (HPPE) matrix have been synthesized and investigated. Shift of the fundamental absorption edge has been shown to be absent with a variation in the nanoparticle size for the given samples and a small disordering of atoms in nanoparticles is observed.     

Synthesis, surface morphology, and optical and structural properties of CdS and ZnS nanoparticles

Synthesis of CdS and ZnS nanoparticles in reverse micelles and organic solvents has been carried out. Particles with a hexagonal structure 2–5 nm in size are formed during synthesis. Maintaining the reaction mixture at room temperature leads to the formation of nanoparticles with a cubic structure 100–150 nm in size. The changes in the optical properties of CdS and ZnS nanoparticles, depending on the synthesis method and conditions and on the precursors used, have been investigated. The luminescence characteristics of local surface defects of nanoparticles depend weakly on nanoparticle sizes. The dependence of the fluorescence and phosphorescence intensity of nanoparticle surface defects on the polarity of surrounding solution is demonstrated; thus, these particles can be used as polarity indicators.     

Investigation of the mechanism of inelastic alpha-particle scattering on 28Si nuclei by the method of angular αγ correlations at E α = 30.3 MeV

The angular dependence of the differential cross sections for alpha-particle scattering on ²⁸Si nuclei and double-differential cross sections for the reaction ²⁸Si(α, αγ)²⁸Si at E _α = 30.3 MeV is measured for the case of alpha-particle emission angle between 20° and 160° and the excitation of low-lying states of the ²⁸Si nucleus (0⁺, ground state; 2⁺ state at 1.78 MeV; 4⁺ state at 4.62 MeV; 0⁺ state at 4.96 MeV; and 3^? + 4⁺, 6.88 MeV + 6.89 MeV). The spin-tensor components of the density matrix for the 2⁺ state at 1.78 MeV and the 4⁺ state at 4.62 MeV in the ²⁸Si* nucleus are reconstructed in a modelindependent way. Seven rank-6 components are reconstructed for the 3^? state at 6.88 MeV. Orientation features of ²⁸Si* are determined. The experimental data in question are compared with the results of the calculations performed under the assumption of the collective-excitation mechanism and by the coupled-channel method.     

Solvency of an Insurance Company in a Dual Risk Model with Investment: Analysis and Numerical Study of Singular Boundary Value Problems

Computational Mathematics and Mathematical Physics - The survival probability of an insurance company in a collective pension insurance model (so-called dual risk model) is investigated in the case...     

On the stability of a self-similar spherical bubble of a scalar Higgs field in de Sitter space

An exact generalized discontinuous solution of the spherical-bubble type is obtained for a scalar Higgs field in de Sitter space. It is shown that the radius of such a generalized bubble evolves in accordance with one of the exact solutions to a dynamical problem considered previously for the bubble radius in the thin-wall approximation, where the bubble-wall thickness is negligible in relation to the bubble radius. Both the generalized solution and the self-similar bubble-type solution that was obtained earlier for the Higgs field in de Sitter space are studied for stability: it is shown that the former is stable, while the latter is unstable in this space. A physical interpretation of the reasons for the instability of the self-similar solution is given.     

Investigation of the structure of lower excited states of the 28Si nucleus in α scattering at Eα = 30.3 MeV

The differential cross sections of the ²⁸Si(α, αγ)²⁸Si reaction at E _α = 30.3 MeV, calculated according to the coupled channel method (CCM) with the FRESCO program, are presented for a wide α-particle scattering region with the excitation of the lower ²⁸Si states (0⁺, ground; 2⁺, 1.78 MeV; 4⁺, 4.62 MeV; 0⁺, 4.96 MeV; 3⁻ + 4⁺, 6.88 MeV + 6.89 MeV). The coupling factors are calculated in the Nilsson model.     

Tensor features and dynamical deformation of the 24Mg(2+) nucleus in the reaction 24Mg(d,dγ)24Mg at E d = 15.3 MeV

The results obtained by reconstructing of the experimental angular dependences of polarization tensors, the tensors of orientation of multipole moments, and the dynamical deformation of ²⁴Mg nuclei produced in the 2⁺ state at 1.369 MeV in inelastic deuteron scattering on ²⁴Mg nuclei at E _d = 15.3 MeV for deuteron scattering angles between 25° and 165° in the laboratory frame are presented. The experimental results are compared with the results of calculations based on various versions of the coupled-channel method. The role of spin-orbit and tensor d ²⁴Mg interactions is discussed along with the influence of the reorientation effect. The correlation features of the 2⁺ state of the ²⁴Mg nucleus at 1.369 MeV that were determined in inelastic deuteron and alpha-particle scattering on ²⁴Mg are compared.     

Optical characteristics of cadmium sulfide nanoparticles synthesized in polyethylene matrix and <Emphasis Type=Italic>ortho</Emphasis>-xylene solution

The properties of CdS nanoparticles synthesized in a polyethylene matrix and an ortho-xylene solution are compared. It is shown that these nanoparticles have different shapes, structures, and degrees of imperfection. Due to these differences, unaggregated nanoparticles in solution exhibit luminescence in contrast to nanoparticles in polyethylene. The stabilization of nanoparticles in polyethylene most probably occurs via OH groups, while nanoparticles in solution are stabilized due to partial interaction with dissolved sulfur. The absorption and luminescence spectra of samples with polyethylene are strongly distorted by reabsorption and scattering, while this effect in solution is absent due to a small concentration of nanoparticles.