SovietRxiv · Open Access in English
Rediscovering the Soviet scientific archive, in English
25357 full-text translations 14926 English PDFs 22539 abstracts
Showing 50 of 4600 papers in Chemistry
This paper examines avalanche-like crystallization of magnesium sulfate heptahydrate from supersaturated solution, focusing on the distribution of right- and left-handed crystals under conditions where crystal multiplication is significant. Experiments in closed vessels at different supersaturations…
This paper reports an experimental search for low-lying collective electronic excitations in benzene predicted near 1.04 eV and 1.68 eV. Using very long optical path lengths in liquid benzene and selected derivatives, the authors recorded absorption spectra in the near infrared and visible regions, …
This paper examines a special case in the crystallographic reconstruction of a point basic system from its vector system, when only one multiple peak is available rather than two. The authors adapt the earlier decomposition algorithm, showing that the second stage yields groups of parallelograms ins…
This paper derives the probability of a nonradiative electronic transition with charge redistribution for a molecule or complex embedded in a polar liquid. Treating the medium as a continuous dielectric described by a frequency dependent permittivity, the authors formulate the problem using a Hamilt…
The paper reports an X-ray crystallographic determination of synthetic calcium chondrodite, Ca5[SiO4]2(OH)2, obtained under hydrothermal conditions relevant to calcium silicate hydration products. Using 500 nonzero reflections, Patterson analysis, electron-density synthesis, and least-squares refine…
A variational procedure is presented for analyzing poorly resolved symmetric isotropic EPR spectra by comparing experimental and theoretical correlation functions in Fourier space. The method uses an analytical expression for the Fourier transform of spectra with Lorentzian and Gaussian line-shape c…
The paper reports an X-ray crystallographic determination of the rare-earth sodium titanosilicate mineral tundrite from the Lovozero massif, addressing uncertainties in its composition and structural formula. Using three-dimensional Patterson, electron-density, weighted synthesis, and difference syn…
The crystal structure of hydrothermally synthesized sodium neodymium germanate, NaNd3[GeO4]2(OH)2, is determined from three-dimensional single-crystal X-ray diffraction data. The compound has a monoclinic centered cell and is described mainly in space group I2/c, with atomic positions obtained from …
This paper reports an experimental study of the enthalpy of the chemically reacting nitrogen tetroxide system involving dissociation to nitrogen dioxide, nitric oxide, and oxygen, with emphasis on conditions where available caloric data were insufficient for reliable thermodynamic descriptions. Enth…
The crystal structure of lanthanum pyrogermanate, nominally La2Ge2O7, was determined to identify the germanium oxygen units present in the compound. Single crystal X-ray diffraction data from a triclinic crystal were analyzed in space group P1bar, with heavy atom positions obtained from Patterson an…
The crystal structure of hydrothermally formed Pr3WO6Cl3 was determined from single-crystal X-ray diffraction data for a hexagonal cell with space group P63/m, using Patterson analysis, electron-density syntheses, and least-squares refinement. The final centrosymmetric model, refined against 923 non…
A new lanthanum oxytungstate with composition 2La2O3·3WO3 was obtained as single crystals from the La2O3, WO3, NaCl system, although it had not been found in the binary La2O3, WO3 system. The crystals formed under isothermal conditions through evaporation of NaCl and partly WO3, with the largest col…
Potassium rare-earth double tungstates KLn(WO4)2 for the lanthanide series from lanthanum to lutetium were synthesized as single crystals by crystallization from a K2WO4 and WO3 melt and examined by powder X-ray diffraction, optical goniometry, and differential thermal analysis. The study distinguis…
This paper examines the mechanism of charge compensation in oxygen-free solid solutions of calcium fluoride with trivalent rare-earth fluorides, using an X-ray diffraction study of a single crystal of composition Ca0.607Ce0.393F2.393. Analysis of reflection intensities, electron-density syntheses, a…
The study determines the crystal structure of the red phosphorescent hydrothermal compound K2Mn2Zn4Si4O15 in order to clarify the crystallographic role of manganese in a luminescent zinc silicate. Single-crystal x-ray data were interpreted in the orthorhombic space group Imm2, with atomic positions …
This paper examines the mechanism of polymorphic transformations in organic molecular crystals, focusing on whether the orientation of a daughter phase is determined by the crystallographic structure of the parent phase. Using polarized-light microscopy to measure changes in extinction directions du…
This paper investigates the formation of protonated molecular ions with mass M plus 1 during thermal ionization of organic compounds on oxidized tungsten emitters, with particular attention to phenol. Mass spectrometric measurements of temperature, pressure, and retarding potential dependences show …
This paper examines the possible natural occurrence of long-lived superheavy transuranium elements in light of theoretical predictions of stability islands and reported cosmic-ray track observations. It estimates potential terrestrial abundances under two formation models, primordial nucleosynthesis…
This paper reports a search for long-lived distant transuranium elements in ferromanganese nodules from the southern Pacific Ocean, motivated by theoretical predictions of stable superheavy nuclei and earlier ambiguous observations of unexplained alpha activity and fission effects. The authors exami…
The paper reports an X-ray crystallographic determination of a hydrothermally synthesized potassium yttrium silicate obtained from the system K2O, Y2O3, SiO2, H2O, initially without a known chemical formula. Weissenberg and diffractometer data were analyzed through Patterson methods, symmetry testin…
The paper determines the crystal structure of synthetic Na,Cd-triorthosilicate, Na2Cd3[Si3O10], obtained hydrothermally as phase L in the Na2O, CdO, SiO2, H2O system. Using Weissenberg X-ray intensity data, Patterson and Fourier syntheses, and least-squares refinement, the authors assign the monocli…
The paper determines the crystal structure of hydrothermally synthesized basic lithium cadmium molybdate, LiCd[MoO4]OH, using X-ray diffraction data supplemented by chemical analysis, thermal analysis, and infrared spectroscopy. The compound is monoclinic, space group P21/a, with four formula units …
This paper develops a matrix method for reducing energy operators in the theory of molecular vibrations, specifically for transforming natural coordinates into symmetry coordinates using group-theoretical representations. It describes procedures for diagonalizing symmetric submatrices associated wit…
This study examines whether radioactive and externally irradiated potassium sulfate crystals retain surface charge, a question difficult to address by conventional electrical measurements because of ionization effects near radioactive samples. Cleavage or fracture surfaces of crystals containing sul…
The study determines the crystal structure of barium tetragermanate, BaGe4O9, in order to test earlier proposals that compounds of this type contain Ge3O9 rings and octahedrally coordinated germanium. Single-crystal X-ray diffraction data were collected with anomalous scattering from barium used to …
This paper examines the crystallographic phase problem for non-centrosymmetric crystals and proposes using two-beam interference of X-ray radiation to obtain phase information not available from reflection intensities alone. Starting from first-order correlation functions for coherent electromagneti…
This paper reports a neutron and X-ray diffraction study of a newly observed suboxide phase in the titanium, zirconium, oxygen system, with composition corresponding to Ti2ZrO. Cast and quenched alloys were examined, and reflection intensities were compared with multiple structural models to determi…
This paper reports interferometric measurements of the relative dispersion of neodymium and samarium trivalent ions with respect to lanthanum ions in aqueous chloride solutions. Using the Puccianti method with a spectrograph and Jamin interferometer, and monitoring temperature differences with a dif…
This paper investigates the density of droplets of structurally modified water, whose previously reported anomalous properties suggested that its density might differ from that of ordinary water. Because only minute quantities were available, the authors used hydrostatic weighing in density-gradient…
The paper reports an X-ray crystallographic determination of the hydrothermally synthesized sodium cadmium silicate Na4Cd2[Si3O10], including its monoclinic cell, space group C2/c, atomic coordinates, and interatomic distances. Patterson and Fourier methods followed by least-squares refinement of 16…
Artificial monoclinic miargyrite, AgSbS2, synthesized from high-purity elements through the cubic modification and prolonged annealing, is examined by nuclear quadrupole resonance of Sb121 and Sb123 nuclei, with supporting microscopic, thermal, and X-ray powder characterization. The observed low-tem…
This paper examines whether gas hydrates can be stabilized in capillaries under conditions where ordinary bulk hydrate formation would not be expected, motivated by Pauling’s hypothesis relating anesthesia to hydrate formation in nerve capillaries. Using chlorine hydrate as an example, it argues tha…
This paper derives computational formulas for crystallographic structure factors and their coordinate derivatives when anisotropic thermal vibrations are included, a case in which standard tabulated formulas for space groups are no longer directly applicable. Using a symmetry-based treatment, the au…
This study examines the surface ionization of the radical C4H10N formed when diethylamine interacts with heated tungsten and oxidized tungsten in weak electric fields. Using retarding-potential measurements in a mass spectrometer, the authors compare the velocity distribution of C4H10N positive ions…
This paper investigates the etching of Yakut diamond octahedra in molten hydroxides, nitrates, and peroxide-containing mixtures of potassium and sodium compounds in air at 560 to 700°C. Etching rates were determined from weight loss and surface area estimates, while etched surface morphology was exa…
The paper presents a method for deciphering a Patterson function by exploiting multiple peaks in the vector system, using two selected peaks to generate quadrilaterals and then successively enlarged polygons that isolate shifted copies of the basic atomic system. The authors argue that comparison an…
Electron paramagnetic resonance measurements at 9320 MHz were used to study pentavalent chromium complexes formed in ethylene glycol from hexavalent chromium compounds or potassium perchromate over 320 to 77 K. In liquid solution the spectra show a line from even chromium isotopes and a four-compone…
Hydrothermal crystallization in iron, alkali metal, and tungstate systems was investigated to obtain and characterize iron-containing tungstates, motivated by the hydrothermal occurrence of wolframite-group minerals. Experiments in stainless-steel autoclaves with titanium liners showed that mixed li…
This study examines the external heavy atom effect on intercombination transitions in porphyrins and metalloporphyrins, using etioporphyrin I and related complexes in alkyl iodide solvents. Fluorescence quenching, lifetime measurements, low-temperature phosphorescence spectra, and pulse spectroscopi…
This paper examines the infrared librational band of liquid water and dilute aqueous acetonitrile solutions, focusing on the complex structure of the broad absorption near 700 cm⁻¹. The authors decompose the spectral contour into three approximately Gaussian components and compare their frequencies …
This study reports quantitative Raman spectral parameters for liquid cyclic polydimethylsiloxanes with ring sizes n = 4 to 7, including frequencies, integral and peak intensities, depolarization ratios, half-widths, relative scattering coefficients, and polarizability derivative tensor components. M…
The infrared vibrational absorption spectra of cyclic polydimethylsiloxanes, [(CH3)2SiO]n with n = 4 to 7, are examined to determine quantitative band parameters previously known mainly from positions and qualitative intensities. Using spectrophotometric measurements over 400 to 3000 cm-1 for pure l…
This paper examines temperature nonuniformity on the faces of Rochelle-salt crystals during growth and dissolution from aqueous solutions, a phenomenon arising from heat release during crystallization and influenced by heat and concentration fluxes near the crystal surface. The authors constructed a…
The paper refines the crystal structure of synthetic yttrium oxysilicate, Y2SiO5, addressing discrepancies in a previous preliminary determination, including anomalous interatomic distances. Using single-crystal X-ray diffraction data from 800 nonzero structural amplitudes across seven reciprocal-la…
Elastic scattering of fast ground state oxygen and nitrogen atom beams by NO and CO molecules is studied to probe short range interaction potentials and possible electronic transitions during collisions. Cross section dependences on beam energy are measured and used to determine parameters of effect…
The paper develops an analytical treatment of crystal face growth by a polynuclear mechanism, relaxing the assumption that each layer is completed by a single two-dimensional nucleus before another appears. Under assumptions of an infinite face, constant growth conditions, point-like supercritical n…
This paper investigates the mechanism of polymorphic transitions from an ordered crystal to a rotational crystalline, or plastic crystal, state, using carbon tetrabromide and hexachloroethane as model substances. Through microscopic observation and measurements of transition temperature delays, the …
This study examines the polymorphic transformation of transparent single crystals of monoclinic red selenium into opaque metallic hexagonal selenium. Using optical polarizing microscopy with controlled heating, microphotography, and Laue X-ray patterns, the author observes nucleation beginning near …
The paper addresses crystal growth at low supersaturation or slight supercooling, where classical two-dimensional nucleation is inadequate and screw-dislocation spiral growth has often been treated as the only viable explanation. It argues, using reported observations of oriented crystallization thr…
