Optical spectroscopy and electronic structure of the Er5Ge3 compound

The results of the study of the optical properties and electronic structure of the Er₅Ge₃ compound have been presented. In the wavelength range of 0.22–15 μm (0.083–5.64 eV), the optical constants have been measured, and the spectral and electronic characteristics have been determined. The spin-polarization calculations of the band spectrum have been performed in the local electron spin density approximation (LSDA) with a correction for strong correlations in the 4f shell of the rare-earth atom (LSDA + U method). The main features of the experimental dispersion dependence of the optical conductivity in the region of quantum light absorption have been interpreted based on the results of calculations of the electron density of states.     

Synthesis,thermal analysis,and crystal structure of potassium triiodomercurate monohydrate

Single crystals of potassium triiodomercurate monohydrate KHgI₃ · H₂O are synthesized and studied by X-ray diffraction: space group Pna2₁; a = 8.57961(11), b = 9.23621(13), and c = 11.38977(16) Å, Z = 4; R= 0.0574. Thermal conditions of decomposition of the compound are studied by differential scanning calorimetry.     

Investigation of phase transitions and thermal expansion of some complex tungsten-containing oxides

The phase transitions have been investigated and the thermal expansion coefficients have been determined in compounds with a structure of brannerite, defect pyrochlore, and tungsten bronze of the general formula M ^I A ^VWO_{6 − δ} (M ^I = □, H₃O, Li, Na, K, Rb, and Cs; A ^V = V, Nb, Sb, and Ta; δ = 0, 0.5) by high-temperature X-ray diffraction and differential thermal analysis. It has been shown that brannerites and tungsten bronze do not undergo phase transitions and the compounds are characterized by a significant anisotropy of the thermal expansion, whereas pyrochlores undergo phase transitions of three types, and thermal deformations in them are determined by the size of M ^I atoms.     

Optical properties and electronic structure of YNi<Subscript>5 − <Emphasis Type="Italic">x</Emphasis></Subscript>Cu<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript> intermetallic compounds

The optical properties of hexagonal intermetallic compounds YNi_{5 − x} Cu _x (x = 0, 1, 2) have been investigated by ellipsometry in the spectral range of 0.22–15 μm. It is shown that the replacement of nickel atoms by copper atoms leads to local changes in the optical-conductivity spectra. A new absorption band is found at 3.5–4.5 eV; its intensity depends on the copper content. The plasma and relaxation frequencies of conduction electrons are determined. The electronic structure and interband optical conductivity of these compounds are calculated within the electron density functional theory using the pseudopotential method. The main parameters of the band structure and the total and partial densities of electronic states are determined. Qualitative agreement is obtained between the experimental and theoretical frequency dependences of the optical conductivity.     

Structural transformations on a platinum surface under mechanical tension

The effect of uniaxial tension on the structure of a recrystallized platinum surface is investigated using low-energy electron diffraction (LEED). The initial LEED patterns indicate that the (111) facet emerges on the surface of a platinum foil after a series of heating cycles under vacuum and in oxygen. After loading at ～80 MPa, the clean platinum surface is characterized by systems of regular and irregular atomic terraces. The regular terraces have a (9(111) × 100) structure. As the load increases to 90–100 MPa, the ordered arrangement of terraces transforms into a disordered arrangement. After the samples are held under these loads for ～2 h, the surface structure undergoes a transformation into the diffraction-disordered state. Under tensile deformation, the island structure of graphite molecules on the recrystallized platinum surface containing ～10 at. % C also undergoes a transformation.     

The attainability and solvability spectra of varieties of Clifford semigroups

Omsk. Translated from Sibirskii Matematicheskii Zhurnal, Vol. 32, No. 5, pp. 59–67, September–October, 1991.     

Resonance excitation of C2H4-molecule luminescence by pulsed high-pressure continously tunable CO2 laser

The visible luminescence of ethylene in a focused 10⁹W/cm² continously frequency-tuned field of a high-pressure CO₂ laser was investigated. Q-branch excitation resonance was observed width of 10 cm^-1. No direct correlation between detailed rotational structure and intensity of luminescence was revealed.     

High-<Emphasis Type="Italic">Q</Emphasis> surface modes in photonic crystal/iron garnet film heterostructures for sensor applications

A novel type of a plasmonic sensor based on a magnetophotonic plasmonic heterostructure with an ultrahigh-Q resonance is considered. A magnetoplasmonic resonance with an angular width of 0.06°, which corresponds to a Q factor of 700 and is a record value for magnetoplasmonic sensors, is experimentally demonstrated. It is shown that, owing to the excitation of long-propagation-range plasmons, the transverse magneto-optical Kerr effect is considerably enhanced and, thus, the sensitivity of the magnetoplasmonic sensor to variations in the refractive index increases to 18 RIU^–1, where RIU is the refractive index unit. Numerical calculations indicate that the parameters of the magnetoplasmonic structure can be further optimized to attain sensitivities up to 5 × 10³ RIU^–1.