The infra-red L.M.R. spectrum of SeH in the X 2Π state

Magnetic dipole transitions between the ²Π_1/2 and ²Π_3/2 components of the ground state of SeH have been observed at about 1780 cm^-1 in a L.M.R. experiment using a CO laser. Transitions have been detected for the four most abundant natural isotopes of Se. The transition frequencies depend primarily on the magnitude of the spin-orbit coupling constant and have been analysed in conjunction with data from the E.P.R. spectrum to yield

The admixture of other electronic states by spin-orbit coupling has been investigated to third order in perturbation theory and found to produce significant effects.     

Measurement of deuterium quadrupole coupling constants of CD3 groups by 1H−{2H} N.M.R. studies of nematic solutions

Analytical expressions have been derived for the transition frequencies and intensities of a partially oriented group of deuterium nuclei with symmetry of the permutation group. Using d ₃-acetone, CD₃COCH₃, dissolved in a nematic solvent, as an example, it is shown how ¹H?{²H} double resonance experiments can be used to determine the relative signs of dipolar and quadrupolar interactions. The magnitude of the quadrupole coupling constant of the ²H nuclei in CD₃COCH₃ is determined.     

Effect of the crystalline electric field on the Néel temperatures of RCu2 compounds

Values for the Néel temperature of the RCu₂ compounds (R=Tb–Tm) have been calculated using a molecular-field model including crystalline-electric-field effect as presented by Noakes and Shenoy. The calculated results show that the unusual behavior, at the Néel temperatures, of these compounds can be explained on the basis of this model.     

Dependence of the intensities of ultrasonic sidebands in the Mössbauer spectrum on the statistics of the acoustic field

The acoustic modulation of quanta is analyzed with regard for dissipation of the energy of the excited mode through resonance (having the acoustic frequency) modes. Given definite assumptions, the Rayleigh-Rice distribution function previously introduced phenomenologically is obtained for the oscillation amplitudes. It is proposed that the intensities of the ultrasonic sidebands be expressed in terms of the parameters m and , which are valid for any degree of sound coherence. The results of numerical computations are given.Translated from Izvestiya Vysshikh Uchebrnykh Zavedenii, Fizika, No. 7, pp. 54–57, July, 1979.In conclusion, the authors express their gratitude to Prof. Sh. Sh. Bashkirov for valuable comments.     

Mössbauer and N.M.R. studies of ErFe2Hx

Hydrides of Intermetallic compounds have been the object of many studies because of their potential applications/1/. Recent papers were devoted to the problem of interstitial site occupation in connection with H-H exclusion rule (d_H–H > 2.1 A). The present work deals with ErFe₂H_X, which has been investigated both by⁵⁷Fe Mössbauer Effect and by¹⁶⁷Er N.M.R. Previous studies were limited to X 2, 3.5, 4.1. Here five values of x (1.45, 1.6, 1.84, 2.6, 3.3) are considered, in order to obtain information on hydrogen location, filling and diffusion as a function of x, and also on hydrogen contribution to the electric field gradient (E.F.G.) and crystalline field at the Rare Earth.     

String solutions in the S2 nonlinear σ-model with a gauge field

A variant of the S² nonlinear -model of Faddeev with an Abelian gauge field is considered. By using a direct variational method we demonstrate the existence of string-like solutions in this model and we establish the regularity of these solutions.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, No. 5, pp. 79–83, May, 1986.     

Analysis of partially oriented AA′XX′ N.M.R. spin systems with the aid of sample rotation. The 19F spectrum of cis-difluoroethylene dissolved in a nematic phase

The spectrum of an oriented AA′XX′ spin system can be analysed to give only the parameters δ_AX, J _AA′, T _AA′zz , J _XX′, T _XX′zz and the combinations (J _AX + J _AX′ + 2T _AXzz + 2T _AX′zz ) and (J _AX - J _AX′ + 2T _AXzz - 2T _AX′zz ). By controlled, slow sample rotation it is possible to determine all these parameters separately, and some of their relative signs. Application of this technique to cis-difluoroethylene confirms the signs of the coupling constants determined by Baldeschwieler et al. The dipolar couplings for cis-difluoroethylene are compared with values calculated assuming the geometry as determined from microwave spectroscopy and including the effects of harmonic vibrations.     

N.M.R. spectra of the XnAA′ Xn′ type

The method described previously for the calculation of the X spectrum for spin systems of of the X_nAA′X_n′ type is extended by means of magnetic equivalence factoring to cases in which the long-range coupling constant J_x is non-zero. This coupling is treated as a first-order perturbation to the energy levels obtained when J_x =0, and it is found that J_x may be measured directly from the separations between easily identified lines in the spectrum. A detailed account of the X ₃ AA′X ₃′ system is given, and the N.M.R. spectrum of fluoro-N,N′-dimethyl-1,3,2,4-diazadiphosphetidine is analysed. The spectral parameters obtained are discussed. A computer programme which calculates the spectra of systems involving magnetic equivalence is used to examine the validity of the approximations in the method.     

Molecular field effects in Mössbauer spectra of FeSb2O4

Mössbauer effect measurements have been made using⁵⁷Fe in FeSb₂O₄. At liquid helium temperature a combined electric quadrupole and magnetic hyperfine interaction is observed withH _eff=185±2 kOe, 1/2e ² qQ=2.94±0.09 mm/sec and =0.37±0.09. The direction ofH _eff is perpendicular to thec axis of the crystal and at 33° to the <110> direction. Thec axis is determined to be the direction of the intermediate principal EFG tensor axis. Calculations are made using a molecular field term in the Hamiltonian for the Fe²⁺ orbitals. The results of these calculations are used to explain the observed values of 1/2e ² qQ and and permit a determination of the ordring of the T_2g orbitals among the T_2g energy levels.     

Some solutions of the Gauss–Bonnet gravity with scalar field in four dimensions

We give all exact solutions of the Einstein–Gauss–Bonnet Field Equations coupled with a scalar field in four dimensions under certain assumptions. The main assumption we make in this work is to take the second covariant derivative of the coupling function proportional to the spacetime metric tensor. Although this assumption simplifies the field equations considerably, to obtain exact solutions we assume also that the spacetime metric is conformally flat. Then we obtain a class of exact solutions.     

Gravitational field of quasistationary concentrated systems with rotation in the newman — penrose formalism. I

A series of solutions of Einstein's equations with term is found; it describes the gravitational field of quasistationary concentrated systems containing electric and magnetic charges. The metrics are of Petrov type D and have rotation and expansion. The solutions are interpreted physically. In this, the first part of the paper, the problem is formulated in terms of the spin coefficient method.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 113–117, March, 1976.     

Gravitational field of quasistationary concentrated systems with rotation in the newman — penrose formalism. II

A series of solutions of Einstein's equations with term is found; it describes the gravitational field of quasistationary concentrated systems containing electric and magnetic charges. The metrics are of Petrov type D and have rotation and expansion. The solutions are interpreted physically. In this, the second part of the paper the complete system of Newman — Penrose equations is integrated under the formulated assumptions.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 118–123, March, 1976.I am also grateful to Yu. S. Vladimirov (M. V. Lomonosov Moscow State University) for his interest in the work.     

Effect of electric field on the spectrum and the persistent current of a quantum ring with two electrons （II） additional effect of a charged impurity

This paper studies the effect of a charged impurity together with or without an external homogeneous electric field on a quantum ring threaded by a magnetic field B and containing two electrons. The potential caused by the impurity has been plotted which is helpful to the understanding of the electronic structures inside the ring. The deep valley appearing in the potential curve is the source of localization, which affects seriously the Aharonov-Bohm oscillation （ABO） of the energy and persistent current. It also causes the fluctuation of the total orbital angular momentum L of the pair of electrons. It is found that the appearance of the impurity reduces the domain of the fractional ABO. During the increase of B, the domain of the integral ABO may appear earlier when B is even quite small. The transition from the localized states to extended states has also been studied. Furthermore, it has deduced a set of related formulae for a transformation, by which an impurity with a charge ep placed at an arbitrary point Rp is equivalent to an impurity with a revised charge ep placed at the X-axis with a revised radial distance Rp. This transformation facilitates the calculation and make the analysis of the physical result clearer.     

Properties of the ground state in a spin—2 transverse Ising model with the presence of a srystal field

The properties of the ground state in the spin-2 transverse Ising model with the presence of a crystal of a crystal field are studied by using the effective-field theory with correlations,The longitudinal and transverse magnetizations,the phase diagram and the internal energy in the ground state are given numerically for a honeycomb lattice(z=3).     

Relaxation effects in the Mössbauer spectra of iron complexes with fatty acids

Six new oxo trinuclear iron(III) complexes of the type [Fe₃O(R–COO)₆(H₂O)₃] X, where X= or Cl^– and R=C₅, C₇, C₈, C₉ were synthesized and investigated by Infra Red, Mössbauer Spectroscopy and magnetic measurements. The data pointed to a high spin state (S=5/2) for iron and for antiferromagnetic interactions. The asymmetrical shape of the Mössbauer doublet and its temperature dependence was treated using the Blume relaxation model. The relaxation process is influenced by both X and R components.     

Scaling of the flow field in a combustion chamber with agas——gas injector

The scaling of the flowfield in a gas--gas combustion chamber is investigated theoretically, numerically and experimentally. To obtain the scaling criterion of the gas--gas combustion flowfield, formulation analysis of the three-dimensional (3D) Navier--Stokes equations for a gaseous multi-component mixing reaction flow is conducted and dimensional analysis on the gas--gas combustion phenomena is also carried out. The criterion implies that the size and the pressure of the gas--gas combustion chamber can be changed. Based on the criterion, multi-element injector chambers with different geometric sizes and at different chamber pressures ranging from 3~MPa to 20~MPa are numerically simulated. A multi-element injector chamber is designed and hot-fire tested at five chamber pressures from 1.64~MPa to 3.68~MPa. Wall temperature measurements are used to understand the similarity of combustion flowfields in the tests. The results have verified the similarities between combustion flowfields under different chamber pressures and geometries, with the criterion applied.     

Reactions of COO− radical-ion with M+ and M3+ states produced in the radiolysis of aqueous solutions

Pure nickel and lithium-implanted nickel were irradiated with 1 MeV electrons at the Argonne HVEM-Tandem facility. The lithium-implanted nickel was not damaged as readily as the pure nickel under 1 MeV electron irradiation in the temperature range 20–600°C. The decreased damage accumulation in the lithiated nickel could arise from both the precipitated lithium and that in solution. The latter could slow down the nickel interstitials produced during irradiation by association, thus enhancing their recombination with vacancies. The interfaces of the precipitated lithium could also act as unbiased sinks for the vacancies and interstitials. Above 600°C, under electron irradiation, a melting process which created small irregular shaped regions occurred in the lithium-implanted nickel. Electron diffraction analysis showed that the compound Li₂NiO₂ was formed inside these regions.     

Developments in geothermal energy in Mexico—part eighteen. History of the exploration of the cerro prieto geothermal field

Exploration of the geothermal field of Cerro Prieto started in the 1960's, including the drilling of wells at depths from 1000 m down to 1300 m, which discharged a large amount of geothermal fluid at high pressure. A simple model of the field indicated a suitable productive area of less than 1 km². More wells were drilled in the 1970's, resulting in an expected suitable productive area of 4 km². In 1986, the known suitable productive area was 25 km². The potential of the field was 1000 MW of power, which ensured the continuous production of the 620 MW already installed [1]. Currently, deep drilling is progressing on the eastern parts of the field, including wells 450 m deep which will eventually lead to a better knowledge of the extent and potential of the field through pressure, temperature and production measurements obtained from exploration wells.     

Short-ranged potential effects on the recurrence spectra of lithium M = 1 atoms in parallel electric and magnetic fields

This paper presents recurrence spectra of highly excited lithium atoms with M = 1 state in parallel electric and magnetic fields at a fixed scaled energy ε = -0.03. Short-ranged potentials including ionic core potential and centrifugal barrier are taken into account. Their effects on the states and photo-absorption spectrum are analysed in detail. This demonstrates that the geometric features of classical orbits are of special importance for modulations of the spectral pattern. Thus the weak polarization as well as the reduction of correlation of electrons induced by short-ranged potentials give rise to the recurrence spectra of lithium M = 1 atoms more compact than that of the M = 0 one, which is in good agreement with the experimental prediction.     

Selective detection of single-enantiomer spectrum of chiral molecules aligned in the polypeptide liquid crystalline solvent: Transition selective one-dimensional 1H–1H COSY

One-dimensional (1D) proton NMR spectra of enantiomers are generally undecipherable in chiral orienting poly-γ-benzyl-l-glutamate (PBLG)/CDCl₃ solvent. This arises due to large number of couplings, in addition to superposition of spectra from both the enantiomers, severely hindering the ¹H detection. On the other hand in the present study the benefit is derived from the presence of several couplings among the entire network of interacting protons. Transition selective 1D ¹H–¹H correlation experiment (1D-COSY) which utilizes the coupling assisted transfer of magnetization not only for unraveling the overlap but also for the selective detection of enantiopure spectrum is reported. The experiment is simple, easy to implement and provides accurate eanantiomeric excess in addition to the determination of the proton–proton couplings of an enantiomer within a short experimental time (few minutes).