The search for and fabrication of materials for the near-infrared range of the spectrum, including telecommunication windows, is an extremely important task in modern technology. This work presents the results of studies on the photoluminescence of CsPbCl3 single crystals with varying contents of ytterbium and erbium impurities, grown using the Bridgman method. The existence of electrically neutral Yb3+-V-Pb-Er3+ complexes within the crystal structure was confirmed. Resonant absorption of excitation radiation lambda = 980 nm by Yb3+ ions reveals a three-step energy transfer channel from Yb3+ to Er3+ ions within a single complex. The estimated quantum yield of up-conversion luminescence at lambda = 524 nm (0.02%) associated with erbium ions indicates the presence of electronic transitions to higher energy levels, with the possibility of subsequent emission within the third telecommunication window.

The extinction cross sections of shell-core bimetallic nanoparticles have been mathematically modeled and studied in two surrounding media, air and organic semiconductors. Silver is used as the core material and gold and copper as the shell materials. Ag-Cu, as well as Ag-Au bimetallic nanoparticles, show an order of magnitude higher intensity of plasmon peaks compared to monometallic nanoparticles in case of air surrounding medium and two orders in case of organic semiconductor. The peak of localized plasmon resonance can be tuned by changing the shell thickness.

Substantial variances in the bulk band gap of lithium tetraborate single crystal determined from numerous theoretical calculations as well as from experimental measurements give rise to the problem what is the true value of Eg for that crystal. In this review, we analyze in detail all available theoretical and experimental data regarding the bulk band gap published by different authors and suggest that the experimental value of = (7.5 ± 0.3) eV determined from the optical absorption edge is the most appropriate value. This is in good agreement with Eg = 7.5 eV calculated via modified linear combination of atomic orbitals (LCAO) method.

We report the results on the optical properties of a nanocomposite that comprises 100 nm in diameter silver nanoparticles and elastic polymer matrix. The nanoparticles form planar two-dimensional array embedded into the polymer. The average distance between nanoparticles is about 100- 200 nm that provides electrodynamic coupling between plasmon resonances in adjacent particles. Stretching of the elastic polymer film leads to the increase of the distance between nanoparticles and, in turn, alters optical response of the array. Changes of the optical properties can be monitored visually as continuous changing of the color of the nanocomposite. Thus, a color-tuning filter is realized. Chromaticity coordinates for this tunable filter are presented in CIE xyY color space.

We report on preparation procedures and thermoluminescent properties of undoped and Ag-doped lithium triborate (LiB3O5) pyroceramics. They are prepared using a technique of special annealing of LiB3O5 glass. X-ray diffraction studies of our pyroceramic reveal formation of a large number of nanosized crystallites within amorphous matrix. The crystalline structure and the nature of thermoluminescence in the LiB3O5 pyroceramic are discussed. We demonstrate that this pyroceramic represents a material promising for radiation dosimetry.

The results on optical studies of LiKB4O7-Ag2O and LiKB4O7-Ag2O-Gd2O3 glasses containing Ag nanoparticles formed during annealing in vacuum and air are presented. Strong bands that appear in optical transmission spectra of the samples correspond to plasmon excitations associated with Ag nanoparticles. The average radius of Ag nanoparticles was retrieved from FWHM of the plasmon bands and found to be 1.8-3.8 nm. Nonlinear optical properties of the glasses were studied by the single-beam Z-scan technique. In particular, influence of Ag nanoparticles on nonlinear refraction n2 and nonlinear absorption β coefficients was investigated.

In present work, the color features of the aqueous silver suspensions were investigated. Color systems CIE XYZ and CIELAB are considered. In the case of low concentrations of nanoparticles chromaticity coordinates were determined from the transmission spectra of the colloids. For high concentrations of nanoparticles, when the multiple scattering effects play a key role and the medium turns to be turbid, the color of nanoparticles was found using the Kubelka-Munk relation. Experimental data is compared with that calculated from the Mie theory. Color features of a planar array of non-interacting silver nanoparticles are discussed for the first time.

In this paper, experimental results on the influence of the substrates of different refractive index on the optical properties of two-dimensional silver nanoparticle array are presented. It is shown that plasmon mode that arises from cooperative interactions between closely spaced nanoparticles exhibit different dependences on the incident angle of light. Those dependencies can be qualitatively explained by the concept of mirror images induced in a substrate. Semiconductor (ITO) substrate possesses higher refractive index which even more affects the optical response of silver nanoparticle array.

We observe time dependent variations in the light intensity transmitted through an aqueous suspension of Fe3O4 nanoparticles caused by applied DC magnetic field. Two types of variations can be distinguished. Fast response takes less than 1ms while slow variations occur at the time interval fromseconds to hundreds of minutes. Possible mechanisms of these variations are discussed. Formation of chain-like structures consisted from iron oxide nanoparticles is responsible for the slow variations. It is also accompanied by a diffraction pattern when the magnetic field is orthogonal to the light beam. Fast variations are due to particle rotation and reorientation of the magnetic moment inside a nanoparticle.

DC magnetic field applied to Fe 3O4 nanoparticle suspension affects its light scattering. Time dependent variations in the light intensity transmitted through a suspen- sion are observed after the magnetic field is switched-on. Two types of variations can be distinguished. Fast response takes less than millisecond while slow variations occur at the time interval from seconds to hundreds of minutes. Possible mechanisms of these variations are discussed.

In this paper, we present the results of calculations aimed at the optical radiation efficiency of Ag and Au nanoparticles, which is defined by the ratio of the scattering cross-section to the extinction one.The calculations were performed using Mie theory formalism for surrounding medium of various refractive indexes.It has been shown that silver nanoparticles exhibit substantially larger optical efficiency in a broad spectral range as compared to gold nanoparticles.The optical efficiency for silver nanoparticles with diameters over 90 nm exceeds 90%.

Calculations are presented and compared with recently available experimental data for the scattering of CH4 from a clean, ordered Pt(111) surface. The theoretical model was used earlier for describing data from the same laboratory for the scattering of CH4 by LiF(001). The results are in good agreement with experiment for both the energy-resolved and total-intensity angular distribution spectra.

Calculations are carried out and compared with data for the scattering of CH 4 molecules from a LiF(0101) surface and for O 2 scattering from Al(111). The theory is a mixed classical-quantum formalism that includes energy and momentum transfers between the surface and projectile for translational and rotational motions as well as internal mode excitation of the projectile molecule. The translational and rotational degrees of freedom couple most strongly to multiphonon excitations of the surface and are treated with classical dynamics. Internal vibrational excitations of the molecules are treated with a semiclassical formalism with extension to arbitrary numbers of modes and arbitrary quantum numbers. Calculations show good agreement for the dependence on incident translational energy, incident beam angle and surface temperature when compared with data for energy-resolved intensity spectra and angular distributions.

Calculations are presented for the scattering of CH4 molecules from a LiF(001) surface. The theory utilized is a mixed classical-quantum model that includes energy and momentum transfers between the surface and projectile for translational and rotational motions as well as internal mode excitation of the projectile molecule. The translation and rotation motions, including multiphonon excitations with the surface, are treated with classical dynamics. Internal vibrational mode excitation of the molecules is treated quantum mechanically with extension to arbitrary numbers of modes and arbitrary excitation quantum numbers. The results of calculations are compared with recent high-precision measurements of the scattering of CH4 molecules from clean, ordered LiF(001). The calculated results for energy-resolved spectra and for the angular distributions are in good agreement with experiment.

Calculations are carried out and compared with data for the scattering of CH4 molecules from a LiF(001) surface and for O2 scattering from Al(111). The theory is a mixed classical-quantum formalism that includes energy and momentum transfers between the surface and projectile for translational and rotational motions as well as internal mode excitation of the projectile molecule. The translational and rotational degrees of freedom couple most strongly to multiphonon excitations of the surface and are treated with classical dynamics. Internal vibrational excitations of the molecules are treated with a semiclassical formalism with extension to arbitrary numbers of modes and arbitrary quantum numbers. Calculations show good agreement for the dependence on incident translational energy, incident beam angle and surface temperature when compared with data for energy-resolved intensity spectra and angular distributions.