Experimental and Theoretical In Situ Spectral Magneto-Ellipsometry Study of Layered Ferromagnetic Structures

JETP Letters - The influence of antiadiabatic phonons on the superconducting transition temperature is considered within Eliashberg-McMillan approach in the model of discrete set of (optical)...     

Thermochemistry of Heteroatomic Compounds. Enthalpy of Dissolution and Vaporization of Selected Trimethylsilyl Di- and Tetrathiophosphates

Russian Journal of General Chemistry - Enthalpy of vaporization (ΔvapH°) of trimethylsilyl esters of dithio- and tetratiophosphoric acids (RX)2P(S)SSiMe3 (X = O, S) have been determined...     

Determination of natural aromatic acids using supercritical fluid chromatography

Derivatives of benzoic and cinnamic acids are secondary metabolites of plants, widely distributed in nature and possessing biological activity. Supercritical fluid chromatography (SFC) is shown to provide a high performance separation of nine most important representatives of this class of compounds with selectivity, dramatically different from the reversed-phase high-performance liquid chromatography. The retention and chromatographic separation parameters of analytes for four stationary phases of different nature are compared and the effect of supercritical fluid parameters and the composition of the mobile phase onto the chromatographic separation are analyzed. The optimal separation is found to be achieved when using a silica-based sorbent with 2-ethylpyridinium linked groups. The proposed approach for determination of the above-mentioned compounds is based on the combination of chromatographic separation with multiwavelength spectrophotometric detection and provides the detection limits in the range of 13.0–51.3 μg/L and the analysis duration about 2.5 min. The approach is successfully tested on real objects, such as different kinds of wine.     

Antiferromagnetic ordering in REM cobaltite GdCoO<Subscript>3</Subscript>

Temperature and magnetic-field dependences of the static magnetization of polycrystalline cobaltite GdCoO₃ have been measured. The magnetic properties of the GdCoO₃ sample have been studied in the paramagnetic and antiferromagnetic states. The magnetic phase diagram has been constructed. The exchange field between the Gd-Gd sublattices and the anisotropy field have been estimated.     

New method for measuring the IR surface impedance of metals

A method for measuring the IR optical properties of metals, which implies the analysis of the angular distribution of the photons emitted from the edge of a metal plate due to the conversion of thermal surface plasmons, has been theoretically and experimentally shown. In this work an increased accuracy of the proposed method in the IR region is demonstrated in comparison with more conventional methods based on the Fresnel formulas. This conclusion is supported experimentally with data obtained from the surface impedance measurement of copper in the range from 8 to 9 μm at 185°C.     

On the stimulated scattering threshold in the field of two-dimensionally localized pump wave at arbitrary scattering angles

In the field of two-dimensionally localized pump wave, the dependences of the threshold of various modes of stimulated scattering on the scattering angle were determined for various medium parameters and pump intensities.     

Spectral-luminescence and quantum-chemical study of the anionic forms of 5-fluorouracil

A spectral-luminescence study of neutral (pH 7) and alkaline (pH 11 and 14) aqueous solutions of the anticancer drugs 5-fluorouracil (FU) and tegafur has been performed. The fluorescence spectra of the N3- and N1-centered anions of 5-fluorouracil, its dianion, and the tegafur monoanion with emission maxima at wavelengths (λ_em) of 358, 372, 366, and 358 nm and photoluminescence quantum yields (φ) of 11.2 × 10^–4, 35.1 × 10^–4, 26.5 × 10^–4, and 8.6 × 10^–4, respectively, have been recorded for the first time. The fluorescence characteristics of the FU anionic forms have been related to the magnetic shielding constant as one of the criteria of aromaticity.     

Multielectron approach to the electronic structure and mechanisms of superconductivity in high-Tc cuprates

A review of recent results for the doping dependence of the Fermi surface and mechanism of pairing in LaSrCuO obtained within the LDA+GTB multielectron approach is given. Both magnetic and phonon contributions to the d_x²-y²-gap are considered.     

Thermochemistry of Vaporization and Solvation of Some Three- and Tetracoordinated Organophosphorus Compounds

Abstract

The vaporization and solvation enthalpies about 100 P(III)- and P(IV)-compounds of different acyclic and cyclic space structure have been determined and analysed.     

Factors affecting photoisomerization of 4-styrylpyridine

Photoisomerization of 4-styrylpyridine at different irradiation wavelengths (λ 365 and 254 nm) and in different solvents was studied by UV and ¹H NMR spectroscopy. A procedure for recording the UV spectra of 4-styrylpyridine dissolved in liquid crystalline films freely suspended within a frame. The results of quantum-chemical calculations of the geometry and UV spectra of 4-styrylpyridine isomers are presented.