Non-spherical dielectric microparticles were suspended in a water-filled cell and exposed to a coherent Gaussian light beam with controlled state of polarization. When the beam polarization is linear, the particles were trapped at certain off-axial position within the beam cross section. After switching to the right (left) circular polarization, the particles performed spinning motion in agreement with the angular momentum imparted by the field, but they were involved in an orbital rotation around the beam axis as well, which in previous works [Y. Zhao et al, Phys. Rev. Lett. 99, 073901 (2007)] was treated as evidence for the spin-to orbital angular momentum conversion. Since in our realization the moderate focusing of the beam excluded the possibility for such a conversion, we consider the observed particle behavior as a demonstration of the macroscopic "spin energy flow" predicted by the theory of inhomogeneously polarized paraxial beams [A. Bekshaev et al, J. Opt. 13, 053001 (2011)].

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Special features of the optical-vortex (OV) beams generated by thick holographic elements (HE) with embedded phase singularity are considered theoretically. The volume HE structure is based on the 3D pattern of interference between an OV beam and a standard reference wave with regular wavefront. The incident beam diffraction is described within the framework of a linear single-scattering model in which the volume HE is represented by a set of parallel thin layers with the "fork" holographic structure. An explicit integral expression is derived for the complex amplitude distribution of the diffracted paraxial beam with OV. The numerical analysis demonstrates that the HE thickness may essentially influence not only selectivity and efficiency of the OV beam generation but also the amplitude and phase profile of the diffracted beam as well as regularities of its propagation. We have studied the generated OV morphology and laws of its evolution; in particular, the possibility of obtaining a circularly symmetric OV beam regardless of the diffraction angle is revealed.

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Based on analysis of optical absorption data for CdS nanocrystals obtained by sol-gel technology in gelatin, we have studied the effect of technological factors (reagent concentrations, gelatin concentration) on the growth process and size distribution of the synthesized nanocrystals. Depending on the reagent concentration, we synthesized CdS nanocrystals with mean radii in the range r _ = 1.9-2.4 nm. We have shown that for a low gelatin content (1%), nanocrystals of different sizes are formed (1.7 nm and 2.6 nm). With an increase in the gelatin concentration, the size dispersion decreases and nanocrystals of a single mean radius (2.3 nm) are formed. We have established a correlation between the size dispersion and the shape of the photoluminescence spectrum of the CdS nanocrystals.Introduction. The physics of nanosized objects is a rapidly developing field, where studies of polymer nanosystems with inorganic semiconductors have stimulated considerable interest. This is because of both their original electrophysical, physicochemical, optical, and other properties, and the possible practical implementation in various instruments and devices, in particular light-emitting diodes [1, 2], photoluminescent and solar cells, biological sensors [3, 4], etc. An important aspect of successful solution of fundamental and applied problems in the physics of nanoparticles and nanosystems is development of the technology for obtaining them. One method for preparing nanoparticles is the colloidal chemical method ("sol-gel" technology), based on chemical reaction between the reagents in solution in the presence of stabilizers. The stabilizer prevents joining of the particles and their further growth, where the particles remain in solution. The colloidal chemical synthesis of nanoparticles is affected by a large number of factors, including the concentration of the starting materials, the type and concentration of the stabilizers, the temperature, the pH of the solution, and the reaction time. The possibility of controlling the synthesis by varying the indicated parameters, with the aim of achieving the required properties of the material (size and crystalline structure, dispersed distribution, electrophysical and optoelectronic properties) is one of the advantages of chemical methods for obtaining semiconductor nanoparticles. An advantage of sol-gel technology is also the possibility of making homogeneous thin films and modifying the sample material to obtain a specific form of the devices with low material costs.The most frequently used stabilizers are organic compounds such as polyphosphates [5][6][7][8], trioctylphosphines [9], and thiols [10]. Using trioctylphosphine/trioctylphosphine oxide, cadmium chalcogenide compounds have been obtained with a narrow particle size distribution. The characteristics of semiconductor materials obtained in the above-indicated stabilizers are presented in [11].The choice of stabilizer is determined by many factors. The major factor is the ability to hinder coagulation of the particles, preventi...

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The thermodynamic functions of YbPO 4 have been determined experimentally in the tempera ture range 6-1745 K. The results have been used to calculate temperature dependent heat capacity, entropy, enthalpy increment, and reduced Gibbs energy of YbPO 4 in the range 6-1800 K. The Gibbs energy of for mation of ytterbium orthophosphate (Δ f G 0 (298.15 K)) has been determined.