Search

The RaF molecule is considered to be a potential candidate to search for the electron electric dipole moment and other effects of the time-reversal $(T)$ and spatial parity $(P)$ symmetries violation of fundamental interactions as well as $T$-even, $P$-odd effects. Recently, the existence of a suitable laser-cooling scheme for this molecule was proven experimentally, R. F. Garcia Ruiz et al. [Nature (London) 581, 396 (2020)]. In the present paper, we study energy levels, $g$-factors, and sensitivities to the electron electric dipole moment as functions of the external electric field for the lowest rotational levels of $^{224,226,228}\mathrm{RaF}$ molecules. The state with zero sensitivity to the electron electric dipole moment suitable to test systematic effects is found. Also energy levels of $^{223,225}\mathrm{RaF}$ as functions of the external magnetic field are calculated for the lowest rotational levels. The values of magnetic fields corresponding to the crossing of the levels of opposite parity are found. For these values of the magnetic field, the off-diagonal matrix element of the nuclear spin-dependent parity violation interaction is calculated. The obtained data can be used to design experiments to search for the $T,P$- and $P$-violating effects using the RaF molecule.

Recently, the first laser spectroscopy measurement of the radioactive RaF molecule has been reported by Ruiz et al. [Nature 581, 396 (2020)]. This and similar molecules are considered to search for the new physics effects. The radium nucleus is of interest as it is octupole-deformed and has close levels of opposite parity. The preparation of such experiments can be simplified if there are reliable theoretical predictions. It is shown that the accurate prediction of the hyperfine structure of the RaF molecule requires to take into account the finite magnetization distribution inside the radium nucleus. For atoms, this effect is known as the Bohr-Weisskopf (BW) effect. Its magnitude depends on the model of the nuclear magnetization distribution which is usually not well known. We show that it is possible to express the nuclear magnetization distribution contribution to the hyperfine structure constant in terms of one magnetization distribution dependent parameter: BW matrix element for 1s-state of the corresponding hydrogen-like ion. This parameter can be extracted from the accurate experimental and theoretical electronic structure data for an ion, atom, or molecule without the explicit treatment of any nuclear magnetization distribution model. This approach can be applied to predict the hyperfine structure of atoms and molecules and allows one to separate the nuclear and electronic correlation problems. It is employed to calculate the finite nuclear magnetization distribution contribution to the hyperfine structure of the

Modern strategies for the safe handling of high level waste (HLW) and its long-term disposal in deep geological formations include the immobilization of radionuclides in the form of mineral-like matrices. The most promising matrices for the immobilization of actinides are ceramic forms of waste based on phosphate minerals such as monazite, xenotime, and cheralite. However, the mechanism of substitution of lanthanides and Y by actinides in phosphate minerals is not entirely clear. We formulated a theoretical model, compound-tunable embedding potential (CTEP), that allows one to predict properties of such crystals with point defects. The reliability of the model is validated by a good agreement of calculated geometry parameters with available experimental data. The substitution of Y in the xenotime crystal by Th and U is studied by relativistic DFT in the framework of the CTEP method, based on constructing the embedding potential as the linear combination of short-range "electron-free" spherical "tunable" pseudopotentials. It is shown on the basis of the proposed model that oxidation state +3 is energetically more profitable than +4 not only for thorium but also for uranium as solitary point defects. This atypical oxidation state of U in the mineral is discussed.

The paper presents the results of studying air turbulence impact on operational accuracy of the total station in automatic mode. The study was carried out in laboratory conditions with the total station Leica TCRP 1201+. Dependencies of accurate aiming on direction, velocity and temperature of air stream were determined. The aiming accuracy was determined at the distance of 18 m. The convector that made the air stream, was positioned at different distances from the total station. The numerous measurements determined root mean square errors of aiming in horizontal and vertical cir-cles and distances. It is stated that the aiming accuracy gets worse when the air temperature increas-es. It is also stated that when laser beam goes through the hot air stream, it deviates. The paper gives the recommendations for reducing errors in automated aiming of the total station if there is a directed air convection.

This paper studies the magnetic moment of the stable nucleus ${}^{207}$Pb by Nuclear Magnetic Resonance (NMR) measurements.By combining complex chemistry in the preparation of the $[{\mathrm{PbF}}_{6}{]}^{2\ensuremath{-}}$, sensitive NMR measurements, and highly accurate relativistic calculations of the shielding corrections, the authors show an improved value.

The existence of the fundamental CP-violating interactions inside the nucleus leads to the existence of the nuclear Schiff moment. The Schiff moment potential corresponds to the electric field localized inside the nucleus and directed along its spin. This field can interact with electrons of an atom and induce the permanent electric dipole moment (EDM) of the whole system. The Schiff moment and corresponding electric field are enhanced in the nuclei with the octupole deformation leading to the enhanced atomic EDM. There is also a few-order enhancement of the T,P-violating effects in molecules due to the existence of energetically close levels of opposite parity. We study the Schiff moment enhancement in the class of diatomic molecules with octupole-deformed lanthanide and actinide nuclei: $^{227}$AcF, $^{227}$AcN, $^{227}$AcO$^+$, $^{229}$ThO, $^{153}$EuO$^+$ and $^{153}$EuN. Projecting the existing experimental achievements to measure EDM in diamagnetic molecules with spherical nucleus ($^{205}$TlF) to the considered systems one can expect a very high sensitivity to the quantum chromodynamics parameter ${\bar \theta}$ and other hadronic CP-violation parameters surpassing the current best limits by several orders of magnitude. It can have a dramatic impact on the modern understanding of the nature of CP-violating fundamental interactions.

Soil water-soluble organic matter (WSOM) is the most dynamic and least stable component of humus. It takes a direct part both in leading soil processes and in the formation of effective soil fertility. Its components are involved in the creation of a water-resistant structure, also exhibit physiological activity, and be of service as energy material by microorganisms. The total content of organic matter in the soils of the Rostov agglomeration varies widely: from 1.5 to 7.0%. Long-term studies of soils of the Rostov agglomeration forest-park zones showed that the organic carbon content in these soils increases under tree vegetation. This is due to changes in microclimate conditions and the associated longer period of vegetation of herbaceous vegetation. The WSOM content was obtained by summing the results of cold and hot extraction in natural soils. Its gradually decreases with depth repeating the profile dynamics of the organic carbon content in general. The surface horizons of native chernozems in a forest park and in a virgin land have the highest content of WSOM. It can be concluded that the WSOM pool is directly proportional to the stock of incoming plant residues. The maximum of extracellular enzymes activity was obtained in upper most biogenic soil horizons in the natural city soils. The highest activity was record for the enzyme, which is responsible for the nitrogen cycle (arginine-aminopeptidase (Agr)) and for the phosphorus cycle (acid phosphatase (Pho)). The enzymes activity decreases down the soil profile. For anthropogenically transformed soils, the WSOM profile distribution indicates a peculiar two-member structure of soil profile. The transformed upper urbiс horizons was demonstrate the absence of any patterns in its distribution. In the buried horizons of Technosols, were have the same profile trends and the same absolute values of the organic carbon content such us presented in native chernozems. Despite the high humus content in natural soils (5–7%), most of it is strongly associated with calcium ions. As a result, WSOM has values not exceeding 0.14% of the soil as a whole, or 4% in terms of organic carbon. For the urban horizons of anthropogenically transformed soils, WSOM values are not exceeding 0.04% of the soil, or about 2% in terms of organic carbon. The inversions of enzyme activity are often observed in anthropogenically transformed soils. The enzymatic activity is higher in buried humus-accumulative horizons of urbostratozems than in overlying horizons of the urbic.

The determination of the matrix elements of single-electron operators for the transitions between electronic states (primarily, the dipole moments of electron transitions) is one of the critical problems in simulating the atomic and molecular spectra. In this study, the efficiency of a simple version of the finite-field method for calculating these values within the Fock-space coupled-cluster theory has been investigated.

Chemical shifts of the Kα1 and Kα2 lines (the 2p3/2 → 1s1/2 and 2p1/2 → 1s1/2 transitions, respectively) of the X-ray emission spectrum of the Yb atom in fluorides have been calculated by ab initio modeling the electronic structure. The valence transition Yb(II) → Yb(III) has been analyzed by examples of YbF2, YbF3, and Yb2F4 molecules and YbF2+ cation. The relativistic pseudopotential and basis sets corresponding to it have been constructed for the ytterbium atom. They were used in calculations by the two-component noncollinear version of the density functional theory (DFT) with the PBE0 exchange-correlation functional. Results for the three-coordinated Yb(II) in the FYbF2YbF dimer demonstrated a very weak dependence of the chemical shift on the coordination number of the Yb atom and on the molecular association of ytterbium difluoride. Chemical shifts of the X-ray emission spectrum for the ytterbium compound are related mainly to the change in the occupation of the 4 f shell.

Physics letters / B 779, 324 - 330 (2018). doi:10.1016/j.physletb.2018.02.024, Published by North-Holland Publ., Amsterdam

Traditional processes of acid-catalyzed hydrolysis of wood are ineffective due to the low quality of formed glucose solutions contaminated with impurities that inhibit fermentation of glucose to ethanol. This problem grows during the hydrolysis of birch wood containing large amounts of hemicellulose. This work proposes producing quality glucose solutions using sulfuric acid (H2SO4, 80%) catalyzed hydrolysis at 25°C the cellulosic products formed during the catalytic peroxide delignification of birch wood. It is established that the composition of cellulosic products strongly affects the contents of glucose, xylose, and impurities inhibiting the enzymatic synthesis of bioethanol: furfural, 5-hydroxymethyl furfural, and levulinic acid. High yields (80.4–83.5 wt %) of glucose are achieved using cellulosic products produced by integrating the processes of sulfuric acid hydrolysis of hemicelluloses from birch wood and peroxide delignification of prehydrolyzed wood in the presence of catalysts: 2% H2SO4 and 1% TiO2. Concentration of inhibitors of enzymatic processes in these hydrolyzates is below the allowable limits. Hydrolyzates with maximum glucose content (86.4–88.5 wt %) and minimum concentration of inhibiting impurities produced by acid hydrolysis of cellulosic products treated with an 18% solution of NaOH. Gas chromatography, HPLC, and chromato-mass spectrometry are used to analyze the composition of hydrolyzates. Cellulosic products are examined by SEM, XRD, and chemical analysis.

Chemical shifts of the Kα1 and Kβ1 lines of X-ray-emission spectra of niobium in oxides (Nb2O5)n, n = 1–4, relative to metal Nb have been calculated. Stoichiometric clusters (Nb2O5)n the electronic structure of which was calculated using accurate relativistic pseudopotentials and two-component version of the density functional theory are considered as prototypes for modeling different crystal forms of niobium(V) oxide. The chemical shifts were calculated using the method based on using the property of approximate proportionality of valence spinors in the core region of the heavy atom [11]. Corrections to values of chemical shifts have been determined with allowance for deviations from the abovementioned proportionality. Rapid convergence of results with respect to the size of the niobium oxide cluster has been demonstrated.