The Fermi surface reconstruction in stripe phases of cuprates

Mean-field study of the stripe structures is conducted for a hole-doped Hubbard model. For bond-directed stripes, the Fermi surface consists of segments of an open surface and the boundaries of the hole pockets which appear in the diagonal region of momenta under certain conditions. Segments of the first type are due to one-dimensional bands of states localized on the domain walls. The relation of bands to the doping and temperature dependences of the Hall constant is discussed. In connection with the observation of quantum magnetic oscillations, a systematic search for the electron pockets has been carried out. It is shown that the formation of such pockets in bilayer models is quite possible.

     

Numerical simulation of the spectrum of X-ray natural circular dichroism in the CsCuCl3 crystal

The possibility of observing x-ray natural circular dichroism (XNCD) in enantiomorphous CsCuCl₃ crystals has been considered. The spectra of XNCD in CsCuCl₃ have been numerically simulated for the K, L1, L2, and L3 x-ray absorption edges of copper, cesium, and chlorine using FDMNES and LMTO programs. It has been shown that the largest value of dichroism signal can be expected near the copper and chlorine L1 edges.     

Accurate Control of Synchrotron Radiation Parameters Using X-ray Acoustic Longitudinal Resonators: Paratellurite (ТeO2) Crystals

Crystallography Reports - When carrying out experiments on the P23 beamline of the Petra III synchrotron source (Hamburg, Germany), high efficiency of X-ray acoustic longitudinal resonators for...     

Combining transmission geometry laser ablation and a non‐contact continuous flow surface sampling probe/electrospray emitter for mass spectrometry based chemical imaging

This paper describes the coupling of ambient pressure transmission geometry laser ablation with a liquid‐phase sample collection into a continuous flow surface sampling probe/electrospray emitter for mass spectrometry based chemical imaging. The flow probe/emitter device was placed in close proximity to the surface to collect the sample plume produced by laser ablation. The sample collected was immediately aspirated into the probe and onto the electrospray emitter, ionized and detected with the mass spectrometer. Freehand drawn ink lines and letters and an inked fingerprint on microscope slides were analyzed. The circular laser ablation area was about 210 µm in diameter and under the conditions used in these experiments the spatial resolution, as determined by the size of the surface features distinguished in the chemical images, was about 100 µm. Published in 2011 by John Wiley & Sons, Ltd.     

Peculiarities of the Dielectric Spectra of Triglycine Sulfate Crystals with a Profile Distribution of Chromium

Crystallography Reports - The temperature evolution of the dielectric spectra of TGS–TGS + Cr crystals (TGS stands for triglycine sulfate) with a periodic distribution of chromium impurity...     

Spin structures and the nature of the pseudogap in cuprates

The spin and charge structures formed in a Hubbard model for a finite two-dimensional cluster have been studied in the mean field approximation. The self-consistent iterative procedure reduces an uncorrelated initial spin distribution into stable structures with characteristic spectral properties. It has been shown that the density of states of the system for any doping has a sharp minimum at the Fermi level, the pseudogap. This means that the pinning of the gap at the Fermi level is not an exclusive property of a superconducting state, but is also typical of a normal state of spin glasses.     

On homogeneous extensions of finite predicate systems

It is shown that any finite n-element predicate system for which any two one-element subsystems are isomorphic is embeddable in a finite (2 ⁿ − 1)-element system having a transitive automorphism group.     

Thin‐layer chromatography and mass spectrometry coupled using proximal probe thermal desorption with electrospray or atmospheric pressure chemical ionization

An atmospheric pressure proximal probe thermal desorption sampling method coupled with secondary ionization by electrospray or atmospheric pressure chemical ionization was demonstrated for the mass spectrometric analysis of a diverse set of compounds (dyestuffs, pharmaceuticals, explosives and pesticides) separated on various high‐performance thin‐layer chromatography plates. Line scans along or through development lanes on the plates were carried out by moving the plate relative to a stationary heated probe positioned close to or just touching the stationary phase surface. Vapors of the compounds thermally desorbed from the surface were drawn into the ionization region of a combined electrospray ionization/atmospheric pressure chemical ionization source where they merged with reagent ions and/or charged droplets from a corona discharge or an electrospray emitter and were ionized. The ionized components were then drawn through the atmospheric pressure sampling orifice into the vacuum region of a triple quadrupole mass spectrometer and detected using full scan, single ion monitoring, or selected reaction monitoring mode. Studies of variable parameters and performance metrics including the proximal probe temperature, gas flow rate into the ionization region, surface scan speed, read‐out resolution, detection limits, and surface type are discussed. Published in 2010 by John Wiley & Sons, Ltd.     

Insertion of ethyl isothiocyanate into tungsten hexachloride: Crystal structure of ethyl-(4-ethyl-5-thioxo[1.2.4]dithiazolidin-3-ylidene)ammonium oxopentachlorotungstate(VI)

A product of the insertion of two isothiocyanate molecules into the same W-Cl bond, namely, W-Cl-WCl₅{N(Et)C(S)N(Et)C(S)Cl} (I), is synthesized by the reaction of WCl₆ with EtNCS in a dichloroethane solution. The hydrolysis of compound I results in the formation of single crystals of the complex . The structure of crystals II is determined using X-ray diffraction. It is demonstrated that structural units of crystals II are the [W^VIOCl₅]^? anionic complexes and the ethyl-(4-ethyl-5-thioxo[1.2.4]dithiazolidin-3-ylidene)ammonium cations.     

Computerized mass spectral analysis of the products of temperature-programmed decomposition of γ-aminopropanetri-ethoxysilane grafted on the surface of silica

The basic components (C₃H₆, NH₃, H₂O, C₂H₄, CH₄, C₂H₂, and HCN) and temperature ranges of their separation in thermal decomposition of -aminopropanetriethoxysilane grafted on the surface of silica were determined with a mathematical program for processing mass spectra. The formation of these components was explained with well-known chemical reactions.Deceased.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 73–76, January, 1990.We would like to thank G. V. Kudryavtsev and L. D. Belyakova for providing the sample, and A. P. Gai and L. T. Zhuravlev for recording the mass spectra.