The Structure and Energetics of HF(H2O) n and HCl(H2O) n Clusters

The Voronoi polyhedrons constructed within the framework of molecular–dynamic model of water clusters are used for the analysis of the hydration of HF and HCl molecules. The metric (lengths, angles, surfaces, and volumes) and polyhedron energy parameters are considered. The quantitative characteristics of hydration are derived on this basis.     

Computer Simulation of the Absorption of CO<Subscript>2</Subscript> Molecules by Water Cluster: 2. The Microstructure

The simulation of the absorption of CO₂ molecules by the (H₂O)₁₀ cluster is performed by the molecular dynamics method using the modified TIP4P model of water. The detailed structure of (CO₂)_i(H₂O)₁₀ clusters (0≤i≤11) is analyzed by the statistic geometry method based on the construction of the Voronoi polyhedra. The obtained distributions of the geometric elements of polyhedra indicate the significant changes in the structure of a cluster after the absorption of one CO₂ molecule. Only polyhedra characterizing the structure of unstable water clusters that absorbed six or seven CO₂ molecules demonstrate a nonsphericity close to the ideal tetrahedron. Linear CO₂ molecule tends to be oriented in a cluster so that the average angle formed by this molecule and permanent dipole moments of water molecules would be equal to about 30°.__________Translated from Kolloidnyi Zhurnal, Vol. 67, No. 3, 2005, pp. 315–321.Original Russian Text Copyright © 2005 by Galashev, Rakhmanova, Chukanov.     

Computer Simulation of the Absorption of CO<Subscript>2</Subscript> Molecules by Water Cluster: 3. Dynamic and Dielectric Properties

Autocorrelation functions of translational and angular velocities of H₂O and CO₂ molecules in (CO₂)_i(H₂O)₁₀ clusters that are generated by the molecular dynamics method, as well as their frequency spectra, are calculated. Self-diffusion coefficients of molecules in clusters are determined. The IR spectra thus obtained and frequency-dependent dielectric permittivity of the clusters indicate the enhancement of absorption of Earth’ thermal radiation by these aggregates with an increase in the number of CO₂ molecules in the aggregates. Dielectric losses also increase with the i number.__________Translated from Kolloidnyi Zhurnal, Vol. 67, No. 3, 2005, pp. 322–327.Original Russian Text Copyright © 2005 by Galashev, Rakhmanova, Chukanov.     

Computer-aided study of oxygen absorption by water clusters. IR spectra of heteroclusters

Spectral characteristics of (H₂O)_n, (O₂)_m(H₂O)_n, and (O)_i(H₂O)_n cluster systems, where m≤2, i≤4, and 10 ≤ n ≤ 50, are studied with the molecular dynamics method using a flexible molecule model. The IR absorption spectra are changed substantially as a result of O₂ molecule dissociation, and in the presence of atomic oxygen in the clusters, the spectra are characterized by a deep minimum at 520 cm^?1. The absorption of oxygen causes a marked reduction in reflection coefficient R of monochromatic IR radiation. The number of peaks in the R(ω) spectra decreases to two in the case of molecular oxygen absorption and is no larger than four in the case of atomic oxygen absorption. The absorption of atomic oxygen by the clusters is also accompanied by a significant increase in the dissipation of energy accumulated by the clusters. This effect weakens when molecular oxygen is absorbed. An increase in atomic oxygen concentration in the clusters renders their radiation harder.     

Application of Molecular Dynamic Simulation of Water Clusters with CO and CO2 Molecules to Binary Nucleation Problems

The thermodynamic properties of pure water clusters and aqueous aggregates with either CO or CO₂ molecule were calculated by the molecular dynamics method. The resulting size dependence of the surface tension of the clusters was used to determine the size of the critical seeds. The rate of homogeneous and binary nucleation in atmospheric air was estimated. The role of polar and nonpolar impurity molecules at the initial stage of steam condensation is discussed.     

New Data on the Isomorphism in Eudialyte-Group Minerals. ХI: Crystal Structure of a Potentially New Mineral—A Case of Complete Substitution of Fe2+ with $${\text{Na}}_{{{\text{2/3}}}}^{{\text{ + }}}{\text{Zr}}_{{{\text{1/3}}}}^{{{\text{4 + }}}}$$ in the Eudialyte-Type Structure

Crystallography Reports - The crystal structure and crystallochemical features of a Fe-deficient zirconium-rich analog of eudialyte from the Lovozero alkaline massif (Kola peninsula) have been...     

New Data on the Isomorphism in Eudialyte-Group Minerals. V: Crystal Structure of an Intermediate Member of the Manganoeudialyte‒Ilyukhinite Isomorphous Series

Crystallography Reports - The crystal structure of a high-symmetry representative of the eudialyte group from the Norra Kärr massif (Sweden) has been investigated by X-ray diffraction analysis...     

Crystal Structure of Cl-Deficient Analogue of Taseqite from Odikhincha Massif

An eudialyte group mineral, found in pegmatites of the Odikhincha massif (the northern part of the Siberian platform), has been investigated using X-ray diffraction, IR spectroscopy, and Raman spectroscopy. The mineral is characterized by a high strontium content and a low chlorine content. It has a trigonal unit cell with the following parameters: a = 14.2700(6) Å and c = 30.057(1) Å; V = 5300.6(1) ų; sp. gr. R3m. The structure has been refined to R = 0.047 in the anisotropic approximation of atomic displacements using 1697F > 4σ(F). The idealized formula (Z = 3) was found to be Na₁₂Sr₂Ca₆Fe ₃ ²⁺ Zr₃NbSi₂₅O₇₂(OH,O)₄Cl(Н₂О)_0.2. The chemical composition and structure of this mineral are close to those of taseqite; however, it differs from the holotype sample by a low chlorine content and peculiarities of cation distribution over basic structure sites. A comparative analysis of strontium-rich eudialytes has revealed their important crystallochemical feature: selective concentration of strontium in the N4 site. Thus, taseqite, along with heterophyllosilicates, may play a role of strontium concentrator in agpaitic pegmatites.     

2,4,6-Triazido-1,3,5-Triazine, 2,4,6-Triazidopyrimidine,and 2,4,6-Triazidopyridine as Precursors of Carbon Nitride Materials

The thermolysis of 2,4,6-triazido-1,3,5-triazine (I), 2,4,6-triazidopyrimidine (II), and 2,4,6-triazidopyridine (III) and its products were studied by DSC, mass spectrometry, IR spectroscopy, and electron microscopy. The thermal transformations of I gave planar nets formed by polyconjugated C–N bonds arranged into bundle aggregates. The thermolysis product of III consists of low-molecular compounds and has globular morphology. The thermolysis of II resulted in a mixture of products of both types, among which the planar nets were dominant. The relationship between the structure of the products of the thermal transformations of I, II, and III and the kinetic characteristics of these processes was discussed.     

A multiple production study of neutral strange particles in νμ CC interactions in the NOMAD experiment

A multiple production study of neutral strange particles in ν_μ charged current interactions has been performed using the full data sample from the NOMAD experiment. This analysis allows one to investigate the mechanisms of strange particle production in neutrino interactions. In this study we have tried to build a model for the production of strange particles, which would allow us to describe our measured rates of neutral strange particles, as well as the rates of the single-, double-and triple-V ⁰ production: Λ, K ⁰, , K ⁰ K ⁰, ΛK ⁰, Λ , K ⁰ , ΛΛ, and K ⁰ K ⁰ K ⁰. The text was submitted by the authors in English.