bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic properties and the distribution of iron ions in voltaites
Authors: Hermon Erika , Haddad Roland , Simkin David , Brandão D. E. , Muir W. B.
Published: April 2011

Four chemically distinct iron voitaites of composition A2R52+Q33+ Al(SO4)12∙18H2O where (A, R, Q) are respectively (K, Fe, Fe) (true voltaite), (K, Fe, In), (NH4, Mn, Fe), and (Tl, Cd, Fe) were prepared by Mereiter who had previously done an X-ray structure determination on this material. These samples were studied by the Mössbauer effect to determine the site preference of Fe2+ and Fe3+ between two nonequivalent octahedrally coordinated sites M(1) and M(2): Magnetization measurements show that the magnetic ions have their free spin moment and that ferrimagnetic ordering takes place below 1 K in the cases where (A, R, Q) in the formula are (K, Fe, Fe), (NH4, Mn, Fe), and possibly in the case (Tl, Cd, Fe). The material (K, Fe, In) is antiferromagnetic with θ = −3 K.
Détection optique de niveaux hautement excités du Ne produits par impact électronique
Authors: Veillette P. , Marchand P.
Published: April 2011

The measurement of the intensity of the radiation emitted in the visible and near ultraviolet by Ne atoms excited by electron impact, as a function of the incident electron energy, shows many structures in the energy range 42 to 54 eV. They are attributed to excitation levels of the form 2s2p6nl, 2s22p4nln 'l' and to negative ion resonances.
The electronic spectrum of F2
Authors: Colbourn E. A. , Dagenais M. , Douglas A. E. , Raymonda J. W.
Published: April 2011

The absorption spectrum of F2 in the 780–1020 Å range has been photographed at sufficient resolution to allow a rotational analysis of many bands. A large number of vibrational levels of three ionic states have been observed and their rotational constants determined. Many perturbations in the rotational structure caused by the interaction between the three states have been investigated and the interaction energies determined. The rotational and vibrational structures of a few Rydberg states have also been analyzed in detail but no Rydberg series have been identified. The difficulties in assigning the observed states are discussed. A 1Σu+ – X1Σg+ emission band system has been observed in the 1100 Å region. An analysis of the bands of this system has allowed us to determine the term values and rotational constants of all the vibrational levels of the ground state with ν ≤ 22. The dissociation energy, D0(F2), is found to be greater than 12 830 and is estimated to be 12 920 ± 50 cm−1.
Sum rules for a bounded electron gas
Authors: Griffin A. , Harris J.
Published: April 2011

A discussion is given of the f-sum rule obeyed by the density response function of a bounded electron gas. Particular attention is given to approximate models for a jellium slab. We prove that RPA infinite barrier models (both classical and quantal) are perfectly consistent with the f-sum rule as well as the related dielectric sum rule. In addition, the classical infinite barrier model is shown to satisfy the surface sum rules of Inglesfield and Wikborg.
The decay of 237Np
Authors: Skalsey M. , Connor R. D.
Published: April 2011

The decay of 237Np has been investigated from singles and coincidence γ-ray spectra acquired using Ge(Li) detectors. Forty-two γ rays have been observed and all but one have been placed in the level scheme of 233Pa. The presence of unobserved transitions of low energy has been confirmed by the coincidence data. Five new γ rays are reported here and a new level in 233Pa at 303.8 keV is proposed.
Atmospheric thermal emission 7–15 μm
Authors: Harrison A. W.
Published: April 2011

Atmospheric thermal emission spectra 7–15 μm have been obtained under clear skies, at different elevation angles and for a spectral slit width of 200 Å. Absolute spectral radiances are compared with those calculated for a layer model of the atmosphere through the use of the radiative transfer equation and using actual altitude profiles of temperature, pressure, and water vapour obtained by balloon sounding concurrently with thermal emission measurements.
Absorption saturable de HITC
Authors: Calzada M. Saenz de la , Lam H. , Denariez-Roberge M. M.
Published: April 2011

We measured the variation of the transmission of solutions of HITC in different solvents as a function of the intensity and duration of the incident pulse. Good agreement is found between our experimental results and the theoretical models proposed by Hercher. The absorption cross section at 6943 Å of the excited first singlet levels is deduced from these measurements. Some applications of the results are discussed.
Hall mobility in strontium titanate at high temperatures
Authors: Perluzzo G. , Destry J.
Published: April 2011

We report on an experimental investigation of Hall mobility in the polar semiconductor SrTiO3, in the temperature range where thermal energies are comparable to the energies of the interacting phonon modes. We find, for all crystals measured, i.e. for charge densities from 9.6 × 1020 cm−3 to 4.1 × 1017 cm−3, a mobility decreasing with an increase in temperature for 300 K < T < 650 K, from ~5 cm2 V−1 s−1 at room temperature to ~1.5 cm2 V−1 s−1 at 650 K. A slight dependence of mobility on charge density is observed, in that the crystals with higher charge density have the higher mobility. Finally, we interpret our results in terms of existing large polaron transport theory.
Single-particle transfer studies of 184Re
Authors: Elmore D. , Alford W. P.
Published: April 2011

The level structure of odd–odd 184Re has been investigated by means of the (3He,d) and (α,t) reactions on 183W and the (d,t) and (3He,α) reactions on 185Re. Measured relative Q values have been used to deduce the 184Re mass. The spectra are interpreted in terms of two-quasiparticle states formed by the coupling of the transferred particle and the odd particle in the target ground state, each in separate Nilsson orbitals. Identification of rotational bands is based on a comparison of the measured cross-section patterns and energy spacings with those predicted with the aid of Coriolis mixing and DWBA calculations. Assignments are proposed, some tentatively, for the bands arising from both the parallel and antiparallel coupling of the 5/2+[402] proton orbital with the 1/2−[510], 3/2−[512], 7/2−[503], and 11/2+[615] neutron orbitals.
The structure of the convection sustained ion sheath
Authors: Smy P. R.
Published: April 2011

The detailed structure of the convection sustained ion sheath has been examined. With Re = vfL/μikTe/e (the electric Reynolds number) and α = (ε0kTe/nee2)1/2(1/L), where vf = plasma flow velocity, μi = ion mobility, k = Boltzmann's constant, Te = electron temperature, e = electron charge, ε0 = permittivity of free space, ne = electron density, and L = characteristic length, it is found that for [Formula: see text], no 'presheath' or diminution of electron density outside the sheath is evident, whereas for [Formula: see text], a very substantial density gradient exists which is in fact similar to the quasi-neutral region which occurs in stationary plasmas. Calculations are presented which enable ion and electron densities and electric field and potential to be calculated through the presheath and sheath regions.
Upper bounds of fissile fuel yield with fusion breeders
Authors: Harms A. A.
Published: April 2011

The maximum fissile fuel production capacity of three conceptual fusion breeder systems is examined on the basis of the dominant isotopic-balance processes. Compact relationships involving system power output, plasma and energy multiplication, and parameters which describe the fuel cycle and neutron spectrum in the blanket are established. It is found that the fusion breeder, as characterized herein, possesses a substantial fissile fuel breeding capacity the extent of which is governed primarily by the neutron spectrum in the conversion blanket and the break-even condition of the plasma.
Gauge hierarchies for chiral SU(N) × SU(N) groups
Authors: Eliezer Shalom
Published: April 2011

We have presented a special case where a hierarchy of spontaneous breaking of the symmetries can be achieved in conventional gauge theories (i.e. the Higgs scalars are elementary bosons and the coupling constants of the quartic interactions are small). We break spontaneously the chiral group SU(N) × SU(N) with Higgs scalars transforming like the (N, [Formula: see text]) representation of SU(N) × SU(N). By minimizing the potential we obtain a set of algebraic equations of the type[Formula: see text]where ηj are the vacuum expectation values of the Higgs scalars and μi2 and Aij are parameters. In order to get a hierarchy of spontaneous symmetry breaking we obtain the condition det Aij = 0.
Shell model calculations for odd-mass A = 51–55 nuclei using a weak-coupling basis
Authors: Benson H. G. , Johnstone I. P.
Published: April 2011

The excitation energies of states belonging to various n1-particle. n2-hole configurations relative to a 56,Ni core are calculated, using, when necessary, truncation based on a weak-coupling model. The calculations account for the occurrence of low-lying five-hole states in 53Mn, reproduce the bands of neutron–hole states observed in 53Cr and 53Fe, and predict the existence of low-lying four-hole states in 55Co.
Determination of electric field gradient parameters in tellurium
Authors: Hamilton K. , Powell B. M. , Martel P.
Published: April 2011

The relative intensities of the Mössbauer doublet in Te have been analysed at 4 K and 80 K by utilizing values of the mean square displacement tensor derived from inelastic neutron scattering measurements. The orientation β of the electric field gradient ellipsoid and its asymmetry parameter η have been determined. At 4 K, β = 90°, η = −0.17 and at 80 K, β = 92°, η = −0.48. A simple 'bond charge' model is proposed in an attempt to understand the discrepancy between these values of the electric field gradient parameters and those obtained theoretically by other authors.
Tl+ trimer centre in KBr crystals
Authors: Tsuboi T.
Published: April 2011

Absorption, emission, and excitation spectra of KBr crystals with high Tl+ concentrations have been investigated at 15 K and 77 K. The absorption bands at 262,229, and 217 nm, which are attributable to a Tl+ trimer centre composed of three Tl+ ions, have been identified with ones related to the A, B, and C bands of a Tl+ monomer centre respectively.
Improved treatment of Pauli operator in calculation of saturation diagrams in 16O
Authors: Padjen R. , Rouben B.
Published: April 2011

The free parameter kF for Fermi momentum appearing in the Kerman–Pal procedure for renormalizing the nucleon–nucleon interaction to second order in nuclei has been eliminated by making use self-consistently of Wong's one-point approximation. Calculations of the saturation diagrams in 16O with this approach reproduce very closely our earlier results with a fixed estimated value for kF.
Rotational flow for the spectra of deformed even–even nuclei using an anisotropic harmonic oscillator force
Authors: Prakash V. R.
Published: April 2011

It is shown that, starting from an anisotropic harmonic oscillator force obtained by including non-rigidity in the rigid body force, it is possible to obtain the rotational flow in two dimensions used in the study of ground-state rotational band spectra of deformed even–even nuclei in the rare-earth region. Using the known quadratic dependence of the vorticity parameter (k) on the nuclear deformation (β), the average potential energy is shown to depend quadratically on β to a first order in β. Finally, the rotational Hamiltonian is expressed purely as a function of β, and a comparison of the same with other model Hamiltonians is done. Also, it is concluded that the adiabatic rotational flow is not physically possible on the basis of the RFM. Throughout this paper, only ground-state rotational bands of even–even spheroidal nuclei are considered.
Coherent state theory of large amplitude collective motion
Authors: Rowe D. J. , Bassermann R.
Published: April 2011

A theory of large amplitude collective motion of a many-particle system is presented, which is relevant, for example, to nuclear fission. The theory is a combination of techniques used in many areas of physics and mathematics. The starting point is the application of the time-dependent Schrödinger equation to generate invariant subspaces of the Hamiltonian in the Hartree–Fock approximation. This is a generalization of the group-theoretical device of generating orbits of a group in the construction of reduced representations. It is shown how solutions of the time-dependent Schrödinger equation can be expressed as instantaneous stationary states of a constrained static Hamiltonian. Thus contact is made with the traditional cranking models and constrained Hartree–Fock theories of large amplitude collective motion. The collective motion is quantized using the Hill–Wheeler–Griffin method of generator coordinates in a basis of generalized coherent states. One is thereby able to exploit much of the theory of harmonic oscillator coherent states, which have been so successfully used in the quantum theory of the laser. The resulting Schrödinger equation for the collective dynamics is expressed both in the Bargmann representation and in the more familiar Schrödinger representation. It is shown that solution of the Schrödinger equation in the small amplitude harmonic approximation reproduces the well-known RPA result. A pilot calculation for 28Si shows that application in large amplitude is also feasible.
Lattice vibrations in copper at elevated temperatures studied by neutron scattering
Authors: Larose A. , Brockhouse B. N.
Published: April 2011

The technique of inelastic scattering of thermal neutrons was used to study the temperature dependence of lattice vibrations in Cu in the range 23 °C to 1063 °C, i.e. up to 20 °C below the melting point, and in the various symmetry directions accessible in a (001) scattering plane. Resolution effects were taken into account in the determination of intrinsic phonon frequencies and linewidths. The results indicate a general softening of the lattice as the temperature is raised, the vibrations of transverse polarization being more strongly affected than those of longitudinal polarization. Even close to the melting point, most phonon lifetimes were sufficiently long to allow the unambiguous observation of one-phonon line profiles. A high resolution study at small wave vectors was also performed in order to determine the temperature variation of the zero-sound elastic constants. Among the points of particular interest is the fact that the frequency of the T1 branch was found to manifest a peculiar behaviour around the reduced wave vector [Formula: see text]; a careful examination did not reveal any corresponding distinctive behaviour in the linewidth (lifetime). A search for possible manifestations of the Kohn effect at high temperature was also performed along the [00ζ]T and [00ζζ]L branches.
Application de techniques de multiplexing holographique à l'interférométrie : I. Holographie multiplex à codage du faisceau objet
Authors: Lessard R. A. , Pagé M. , Boivin A.
Published: April 2011

Holographic interferometry is a measurement technique through which displacements or deformations of objects may also be made evident to qualitative observation. For this type of interferogram the signals recorded usually arise from a well-defined portion of the phenomenon under study. This selection of the information to be recorded will therefore necessitate a preliminary knowledge of the course of the phenomenon. In multiplex holographic many signals are recorded over the same photographic medium so that, by proper coding of a sequence of signals, these can be made to interfere two at a time when reconstructed. When multiplexing is achieved by object beam coding, studies of possible applications have shown that the procedures of Fourier transform holography using a lens and orthoscopic pupil mask multiplexing may both serve to code optical informations from a phenomenon and provide, after decoding, an interferometric analysis of this same phenomenon.[Journal translation]
A product representation for cubic harmonics and special directions for the determination of the Fermi surface and related properties
Authors: Fehlner W. R. , Vosko S. H.
Published: April 2011

A product representation of the fully symmetric cubic harmonics has been developed which greatly simplifies the analysis of problems involving these functions. An important example is the determination of special directions which optimize the description of various physical quantities with cubic symmetry. For example, one can obtain for a metal the Fermi energy, density of states, and details of the Fermi surface by calculation or measurement along a few special directions in the irreducible segment of the Brillouin zone. These special directions are also the basis for high-precision formulae for integration over the unit sphere of functions with full cubic symmetry. We obtain such integration formulae with a generalization to two dimensions of the one-dimensional Gauss technique. These new formulae represent a major advance in precision for with them one can determine accurately nearly as many coefficients in a cubic harmonic expansion of a physical variable as there are sample values of the variable. The integration formulae presented here should be adequate for most situations of current physical interest; if not, the method described in this paper can be used to obtain formulae with even higher precision.
Neutron scattering studies of the dynamic structure of liquid 4He
Authors: Svensson E. C. , Martel P. , Sears V. F. , Woods A. D. B.
Published: April 2011

Several aspects of the dynamic structure of liquid 4He have been studied by means of neutron inelastic scattering at selected temperatures, pressures, and values of the wave vector transfer Q. In particular, the Van Hove scattering function S(Q,ω) has been determined for Q = 3.0 nm−1 at 1.2 and 2.3 K at saturated vapor pressure (SVP), for Q = 8.0 nm−1 at 1.2 K and SVP, and for Q = 11.3 nm−1 (near the first maximum of the dispersion relation) and Q = 20.5 nm−1 (near the roton minimum) at 1.2 K and pressures of 0.07 and 2.4 MPa (just below the melting pressure). S(Q, ω) changes markedly with pressure; most strikingly, the intensity of the sharp 'one-phonon' peak at Q = 11.3 nm−1 decreases by about a factor of two between 0.07 and 2.4 MPa. For Q = 3.0 nm−1 and T = 1.2 K, the 'multiphonon' peak is sharp and symmetrical and centred at a frequency significantly greater than twice the roton-minimum frequency. For the higher Q values, the 'multiphonon' component exhibits a complex shape with a long high-frequency tail. The results appear to be describable in terms of one-phonon and multiphonon scattering with no indication that it is necessary to invoke the existence of two-roton bound states. They do, however, indicate that there is a strong interference between one-phonon and multiphonon scattering processes which in turn indicates that liquid helium is very 'anharmonic'.
Sum-coincidence studies in the decay of 59Fe
Authors: Chaturvedi Lakshman , Prasad Rajendra , Chaturvedi S. N. , Nigam A. K.
Published: April 2011

The level structure of 59Co has been examined using the sum-coincidence technique. Sum-coincidence spectra at 1482, 1434, and 1291.6 keV sum gates were recorded to establish the presence of a weak 189 keV gamma ray between the 1482 and 1291.6 keV states, which is very close to the intense 192 keV gamma ray.
The 1S0 two-nucleon T matrix and the interior wave function
Authors: Hodgson R. J. W. , Tan J.
Published: April 2011

The fully off-shell T matrix is generated from a real symmetric function σ(k,k′) which in turn can be obtained from a knowledge of the two-body wave function in the interaction interior. The resulting T matrices are employed to compute the binding energies of 16O, 40Ca, and nuclear matter. Limiting the two-body wave function to physically acceptable forms limits the allowed σ functions. A 'difference integral' is defined in terms of the two-body scattering wave function, which seems to be strongly correlated with the binding energies.
Resistivity of thin TaS2 crystals
Authors: Tidman J. P. , Frindt R. F.
Published: April 2011

Resistivity measurements on thin crystals of 1T-, 2H-, and 6R-TaS2 show that anomalies persist down to sample thicknesses of 100 Å. The resistivity of 1T-TaS2 can be described by an activation energy of 5 meV between 50 and 150 K. 6R-TaS2 is metallic and has resistive anomalies around 325 K.
Boltzmann–Langevin equation and light scattering by dilute gases
Authors: Zardecki Andrzej
Published: April 2011

The Boltzmann–Langevin equation, which is the linear Boltzmann equation supplemented by a fluctuating force term, is used as a starting point to analyze the density correlation function in a dilute gas. By referring to the fluctuation–dissipation theorem, an equivalence of this approach and the conventional treatment based on the kinetic equation is established. For molecular gases, a quasi-classical description is employed, permitting one to incorporate internal degrees of freedom into the theory. With the help of Zwanzig's projection operator formalism, a new simple computational procedure is developed. Its versatility is illustrated by the explicit calculation of the scattered light spectrum from H2 and HD for two specific models.
Electron capture to positron emission ratio in the decay of 44Sc
Authors: Stocker H. , Baerg A. P.
Published: April 2011

A new measurement of the total electron capture to positron emission ratio, e/β+, for the allowed beta decay of the ground state of 44Sc has been carried out by a 4πβ–γ coincidence technique using a pressurized gas proportional 4πβ counter and a Ge(Li) γ detector. The result is 0.0497 with a standard error of 0.0023 and an estimated maximum systematic uncertainty of 0.0026. By this method, the total uncertainty in the measured ratio has been reduced by about a factor of three compared to the most accurate of earlier results. The present value of e/β+ is in good agreement with all current theoretical estimates for allowed transitions and a detailed summary of these estimates is presented.
Optical studies of Tl2+ centres in X-rayed KI:Tl crystals
Authors: Tsuboi Taiju
Published: April 2011

The absorption spectra of KI crystals with high Tl+ concentrations (0.01–2.0 mol%) have been measured after X-ray exposure at 77 K or 120 K. A new band has been observed at 1800 nm. It is suggested, from the correlation of the 1800 nm band with the (Tl+)2, Tl0, and Tl++ bands, that the 1800 nm band is ascribed to Tl2+ centres which are formed when (Tl+)2 centres capture electrons created in the crystal by the X-ray exposure or released from Tl0 centres.
Shift of holes in spectral lines due to time dependent perturbation
Authors: Srivastava R. P.
Published: April 2011

The radiative decay of an atom with two excited states, one decaying and the other non-decaying, coupled by a time dependent perturbation, is investigated. The hole in the emission line is found to be shifted by an amount equal to the frequency of the time dependent perturbation. The practical importance of this effect is discussed. It is also noticed that the two methods of solution, one by making the rotating-wave approximation and the other by a perturbation expansion, yield different results, especially in the case when the two excited states are strongly coupled.
A Langmuir probe technique for measuring temperatures in a flame plasma
Authors: MacLatchy C. S. , Miner J. R.
Published: April 2011

A simple method of measuring the temperature of a flame is presented. It is based on the use of a Langmuir probe and the assumption that the flame exhibits local thermal equilibrium so that the Saha equation can be applied. The method has been compared to measurements of temperature based on the relative emissivity of the Na D line at 5896 Å and shows good agreement except in regions where the flame is greatly perturbed or steep temperature gradients exist.
A note on a theory of gravity
Authors: Rastall Peter
Published: April 2011

An error in a previously published theory of gravity is corrected. Field equations are derived from a Lagrangian density of simple mathematical form. The post-Newtonian approximation is calculated, and the theory is shown to be in agreement with all local observations. The limitations of the standard, parameterized post-Newtonian theory are noted.
The 2506–2159 keV transition in 60Ni following beta decay of 60Co
Authors: Logan B. A. , Dixon W. R. , Storey R. S. , Ljubičić A.
Published: April 2011

A Ge(Li)–NaI(Tl) coincidence arrangement has been used to verify the presence of a 347 keV γ ray following the beta decay of 60Co. This γ ray is identified as the 2506 → 2159 keV transition in 60Ni. The intensity was measured to be (6.9 ± 1.0) × 10−5 per beta disintegration of 60Co. An upper limit of 1.2 × 10−5 per beta disintegration (95% confidence limit) was obtained for the 2626 → 2159 keV transition in 60Ni.
Material lines in viscous and elastic flow between eccentric co-rotating cylinders
Authors: Chaffey Charles E. , Buda Peter de
Published: April 2011

The two-dimensional geometry of two eccentric cylinders is fixed by the ratio of radii and the eccentricity; the relation of these to coaxial (bipolar) coordinates is illustrated. When a Newtonian fluid is between the cylinders and they rotate with equal angular velocity in the same direction, the fluid in the middle of the gap lags behind the walls, not returning to its original position after one revolution. Calculated material lines at successive times, streamlines, and pressure and vorticity contours are illustrated for four configurations. Flow is shearing rather than extensional. Accurate pressures agree with crude estimates based on drag and pressure flows within a factor of four. An eddy circulates in the wide part of the gap when the eccentricity is greater than a critical value dependent on the ratio of radii. When the material in the gap is purely elastic, adhering to the walls, the stress oscillates with time unless the stress-free state is concentric. Infinitesimal elasticity theory is used to calculate steady stress and displacements. The stress agrees exactly with that deriving from Abbott and Walters' theory.
Photodisintegration cross sections of the deuteron
Authors: Rustgi M. L. , Rustgi O. P. , Sandhu T. S.
Published: April 2011

Employing a variety of local static potentials, the bremsstrahlung-weighted and integrated cross sections for the photodisintegration of the deuteron are calculated. The effect of variation of the tensor force in the two-nucleon Yale potential in a manner as to affect only the D state probability of the deuteron, while leaving the values of the other two-body observables unchanged, is studied. It is found that though the contribution of the central, tensor, and spin–orbit components of the two-nucleon potentials to the integrated cross section may vary significantly, the integrated cross section does not change by more than a few percent. The sensitivity of the integrated cross section to the short-distance features of the two-nucleon local potentials is also studied.
Intensities and spin decoupling in the ScO emission spectrum
Authors: Féménias J.-L. , Goure J. P. , Stringat R.
Published: April 2011

Previous work on the theoretical study of the intensity distribution in the emission spectrum of ScO is now extended and a comparison is made with some experimental spectrometric data, and some physical results such as the temperature of emission and the 'spin allowed' property of the A2Π → X2Σ transition are given and discussed. The great influence of the slight spin decoupling of the A2Π (case (a)) state on the intensity distribution is shown and is explained theoretically using the mixing coefficients obtained in a former rotational study of the spectrum.
Sunrise measurements of stratospheric nitric oxide
Authors: Ridley B. A. , McFarland M. , Bruin J. T. , Schiff H. I. , McConnell J. C.
Published: April 2011

The chemiluminescence technique has been used to measure the growth of stratospheric nitric oxide from before sunrise until about 2 h prior to local noon at a constant altitude of 26.5 km at 33.1 °N. The instrument has sufficient time resolution to record the rapid growth of NO due to photolysis of NO2 during ultraviolet sunrise. As well, NO was observed to increase slowly throughout the remainder of the experiment. This slow growth is tentatively assigned to the release of NO2 and NO3 and subsequently NO from the photolysis of N2O5 formed during the night. A time dependent computer simulation of diurnal measurements is used to investigate the sensitivity of the computed NO growth curves to O3, total NOx, and the photolysis coefficient of N2O5.
Asymmetric excitation of the isobaric doublet 9Be–9B through the 9Be(p,pn)8Begs reaction
Authors: Jérémie H. , Kennedy G.
Published: April 2011

A measurement of the energy spectrum of protons from the 9Be(p,pn)8Begs reaction (Ep = 12.7 MeV, θp = θn = 45°) shows strong excitation of the [Formula: see text] state in the n–8Be system, but not in the p–8Be system. In the region of low relative energy in the p–8Be system one observes a broad continuous spectrum of protons, which can be qualitatively explained by a modification of the attenuation model of Rogers and Saylor for quasifree scattering.
Photoconductivity study of amorphous CdTe
Authors: Shiah R. T. S. , Brodie D. E. , Eastman P. C.
Published: April 2011

Photoconductivity measurements as a function of light intensity and temperature for amorphous CdTe are analyzed on the basis of the Mott and Davis model and some ideas of the Arnoldussen, Bube, Fagen, and Holmberg model. Energy parameters within the mobility gap of amorphous CdTe were evaluated. The effective density of localized states is found to be 1017and 1019 per cm3 per eV near the valence and conduction band edges respectively. The localized-to-localized recombination transition rates are also given. The dark Fermi level is found to be 0.54 eV above the valence mobility edge. Localized states extend into the mobility gap 0.37 eV from the valence mobility edge. These results are consistent with earlier measurements by Ng, Webb, and Brodie.
Relaxation processes of some simple aliphatic molecules in dilute solutions
Authors: Madan M. P.
Published: April 2011

The dielectric relaxation processes of acetone, cyclohexanone, 4-methyl-2-pentanone, and 4-heptanone in dilute nonpolar solvents, n-heptane, cyclohexane, benzene, and carbon tetrachloride have been studied in the microwave region over a temperature range 10 to 60 °C. The relaxation times and the thermodynamic parameters for the activated states have been determined using the measured dielectric data. The results have been discussed in terms of dipole reorientation by molecular and intramolecular rotation and compared, wherever possible, with other similar studies on aliphatic molecules.
Diffraction by a half-plane perpendicular to the distinguished axis of a general gyrotropic medium
Authors: Przeździecki S. , Hurd R. A.
Published: April 2011

An exact, closed-form solution is found for the following half-plane diffraction problem: (I) The medium surrounding the half-plane is both electrically and magnetically gyrotropic. (II) The scattering half-plane is perfectly conducting and oriented perpendicular to the distinguished axis of the medium. (III) The incident electromagnetic plane wave propagates in a direction normal to the edge of the half-plane.The formulation of the problem leads to a coupled pair of Wiener–Hopf equations. These had previously been thought insoluble by quadratures, but yield to a newly discovered technique : the Wiener–Hopf–Hilbert method. A basic feature of the problem is its two-mode character i.e. plane waves of both modes are necessary for the spectral representation of the solution. The coupling of these modes is purely due to edge diffraction, there being no reflection coupling. The solution obtained is simple in that the Fourier transforms of the field components are just algebraic functions. Properties of the solution are investigated in some special cases.
Long wavelength optic phonons in WSe2
Authors: Mead D. G. , Irwin J. C.
Published: April 2011

The first order Raman spectrum of the layer type semiconducting compound, WSe2, has been investigated. The frequencies of the Raman active A1g, E2g1E1g, and E2g2 modes have been determined to be 253,250, 178, and 25 cm−1 respectively. Using a scaling relation the results have been compared to the values obtained previously for the isostructural compound 2H—MoS2. The good agreement that is obtained between the measured and calculated values is taken as corroboration of the present assignments in WSe2.
The 4550 Å band system of glyoxal. IV. Vibration–rotational analyses for 11 bands of 13C2H2O2 and determination of molecular geometries
Authors: Birss F. W. , Braund D. B. , Cole A. R. H. , Engleman Jr. R. , Green A. A. , Japar S. M. , Nanes R. , Orr B. J. , Ramsay D. A. , Szyszka J.
Published: April 2011

Rotational analyses have been carried out for 11 bands of the [Formula: see text](π*–n) system of 13C2H2O2 in absorption. Approximately 12 000 lines have been assigned, and rotational and vibrational constants have been evaluated. The following vibrational frequencies have been determined: ν2′ = 1365.17 cm−1, ν4′ = 918.81 cm−1, ν5′ = 502.48 cm−1, ν7′ = 229.40 cm−1, ν7″ = 124.61 cm−1Using the rotational constants for C2H2O2, C2HDO2, C2D2O2, 13C2H2O2, and C2H218O2, the following geometrical parameters have been evaluated: in the Ã1Au excited state, r0(CH) = 1.115 ± 0.010 Å, r0(CO) = 1.252 ± 0.016 Å, r0(CC) = 1.460 ± 0.025 Å, [Formula: see text], [Formula: see text]; in the [Formula: see text] ground state, r0(CH) = 1.109 ± 0.008 Å, r0(CO) = 1.202 ± 0.012 Å, r0(CC) = 1.527 ± 0.017 Å, [Formula: see text], [Formula: see text]. The ground state parameters are in excellent agreement with earlier electron diffraction results.
Photoneutron cross sections in 7Li
Authors: Ferdinande H. , Sherman N. K. , Lokan K. H. , Ross C. K.
Published: April 2011

Photoneutron energy spectra from 7Li have been measured by time-of-flight methods, for bremsstrahlung end-point energies increasing in 2 MeV steps from 13 to 25 MeV. The ground-state and approximate first-excited-state differential cross sections at 90° have been obtained from 8.5 to 23 MeV. No pronounced fine structure has been observed. The measured branching ratio to the first excited state falls from an average value of 0.70 between 10.3 and 14.5 MeV to an average of 0.29 between 14.5 and 18 MeV, and rises again to an average of 0.38 between 18 and 23 MeV. This behaviour can be explained by a crude theoretical model in which 1p → 2s and 1p → 1d single particle transitions dominate below 18 MeV. The calculation predicts a branching ratio of 0.50 near threshold, falling to 0.23 at higher energies, in reasonable agreement with the experiment. The integrated value of the ground-state cross section up to 23 MeV is about (38.7 ± 3.9) MeV mb, while that for the first excited state is about (17.2 ± 3.4) MeV mb. Together they account for 39% of the exchange-augmented dipole sum of 7Li.
Etude de la bande 2ν4 du méthane
Authors: Pierre G. , Cadot J. , Corice R. J. , Fox K.
Published: April 2011

The band 2ν4 of methane has been studied with the aid of a tensor formalism; 9 constants have been determined from 83 observed transitions. The attribution of these transitions has been made from a spectrum recorded, at low temperature (100 K), on the grille spectrometer of the Laboratory of Molecular Spectronomy at Dijon.The root-mean-square deviation obtained is 0.14 cm−1, and the comparison between the spectrum calculated for T = 100 K and that recorded cold is excellent.
A new predissociated 2Σ+ state of the BeCl molecule
Authors: Carleer M. , Burtin B. , Colin R.
Published: April 2011

Ten bands belonging to a new B2Σ+–X2Σ+ system of the BeCl molecule have been discovered in emission between 1990 and 2175 Å. The bands of both isotopes Be35Cl and Be37Cl have been photographed at high resolution and the most intense ones have been rotationally analyzed. Only three levels of the excited state have been observed and they present vibrational and rotational perturbations. The principal molecular constants of the new B2Σ+ state of Be35Cl are: v00 = 48 827.6, ΔG1/2 = 925.5, ΔG3/2 = 1212.7, Be = 0.7751, De = 3.5 × 10−6 cm−1, and the equilibrium internuclear distance is 1.7422 Å. The unusual intensity distribution in the bands can be tentatively interpreted as the result of an inverse predissociation which leads to a value of D″0 = 27 800 ± 500 cm−1 (3.45 ± 0.06 eV) for the dissociation energy of the ground state of the BeCl molecule. This value is at variance with thermochemical data.
A Raman scattering study of the solid phases of HCl, DCl, HBr, and DBr
Authors: Vesel J. E. , Torrie B. H.
Published: April 2011

Raman scattering studies were carried out on the ferroelectric and paraelectric phases of HCl, DCl, HBr, and DBr at temperatures from ~72 to ~160 K. Changes in the lattice region spectra at temperatures near Tc confirm the order–disorder nature of the ferroelectric transitions and the importance of anharmonic effects in these materials. The structural transition occurring in HCl near 120 K was observed by internal mode depolarization measurements which change irreversibly; these changes are attributed to macroscopic disorder in the sample below this temperature. Observations of the internal modes of HBr show a thermal hysteresis around an intermediate cubic phase and analogous results obtained for DBr imply the existence of a new phase which is similar to the intermediate phase in HBr.
Ionization energies of the hydrogen molecule ion in strong magnetic fields
Authors: Lai C. S. , Suen B.
Published: April 2011

The variational principle is used to determine the ionization energy and equilibrium internuclear separation of a hydrogen molecule ion in the presence of magnetic fields of strength up to [Formula: see text]. The trial wave functions used are made of some linear combinations of the unperturbed wave functions of the hydrogen atom. The results are shown to be better than those of de Melo, Ferreira, Brandi, and Mirandi for fields less than ~3 × 1010 G.
Electron motion and the Hall effect in monocrystalline zinc
Authors: Hurd C. M. , Alderson J. E. A. , McAlister S. P.
Published: April 2011

The Hall resistivity ρ21(B, T) observed in Zn when [Formula: see text] and [Formula: see text] has been measured in fields B = 0.1–2.0 T and at temperatures T = 1.7–680 K. Supporting measurements of the transverse magnetoresistance have also been made at 1.7 K. A qualitative analysis of ρ21(B, T) is given separately for the cases when the cyclotron motion is confined to an axial or to the basal plane. In the latter case, the discussion is supported by path integral calculations based upon model orbits chosen to imitate all the geometrical possibilities arising from magnetic breakdown between the monster and needle sheets. The results provide an explanation of the principal features shown by ρ21(B, T).
Bond percolation and cluster formation on random lattices
Authors: Wintle H. J. , Williams T. P. T.
Published: April 2011

We have studied the formation of clusters and the distribution of bonds between sites on random lattices by Monte Carlo and analytic techniques for coordination numbers in the range 3 ≤ z ≤ 12. A comparison between Cayley trees (Bethe lattices) and systems in which closed loops are allowed (cyclic systems) indicates little difference in cluster formation but considerable differences in bond distribution between these two types of lattice. The results suggest that there is little difference between the percolation limits for the two types (at constant z), contrary to the existing results for disordered systems. This work points out a possible weakness in the analytic treatments of the Cayley tree due to the omission of correlation effects, and it also suggests that stochastic treatments of cyclic systems overestimate the critical bond number for percolation.
Photoinjection into polyethylene terephthalate
Authors: Sapieha S. , Wintle H. J.
Published: April 2011

We have measured the photocurrents injected into polyethylene terephthalate from evaporated aluminum electrodes in the wavelength range 475–300 nm following a careful depolarization of the specimens. The yield curves give linear plots of (yield)1/2 against photon energy. The threshold energy is [Formula: see text]. Using fields up to 4 × 105 V cm−1, the threshold falls at a rate consistent with Schottky injection of holes, while the yield itself increases as expected for geminate recombination. Our yield results agree with those obtained using electron beam excitation, but differ from the case of hard X-ray irradiation.
NMR in single crystals of Ca(OH)2
Authors: Holuj F. , Wieczorek J.
Published: April 2011

Single crystals of Ca(OH)2 were studied at 25 °C and −170 °C by the NMR method. The method of moments which included the vibrational correction was used to analyze the results with a view to comparing the position of the proton in the single cell obtained by this method, with that obtained by other methods. The agreement with neutron diffraction data is close.
Microwave absorption in gaseous SF6 in the region of 2.3 cm−1
Authors: Urbaniak J. L. , Reesor G. E. , Dagg I. R.
Published: April 2011

Microwave absorption in gaseous SF6 is reported at 295 K in the density range 15–30 amagat and in the region of 2.3 cm−1. The microwave results are compared with the extrapolated infrared results.
X-ray study of the twinning and phase transformation of phosphocristobalite (AlPO4)
Authors: Ng H. N. , Calvo C.
Published: April 2011

Crystals of the cristobalite polymorph of AlPO4 (phosphocristobalite) up to 3 mm in breadth were grown from a V2O5 flux. In the α phase (C2221), the presence of twin domains prevents an accurate resolution of the structure as a function of temperature. The six twin components of this phase readily lead to a disordered β phase [Formula: see text] with short range correlations as suggested previously. The α–β transformation is first order with a substantial hysteresis in the transition temperature.
The magnetic phase transition in MnO
Authors: Boire R. , Collins M. F.
Published: April 2011

We have confirmed that the magnetic phase transition in MnO is first order at 117.5 ± 0.5 K. The sublattice magnetization curve appears to be of the general form appropriate for a critical phase transition up to a sudden drop to zero a few degrees short of the 'virtual' critical transition temperature. Our results do not show the anomalies on the nuclear Bragg peak at the transition temperature that were reported by Konstantinovic and Babic.
Spin-waves in CsMnF3
Authors: Khatamian D. , Collins M. F.
Published: April 2011

The spin-wave dispersion relations were determined by neutron inelastic scattering for the high symmetry directions (0 0 ξ) and (ξ 0 0) in the hexagonal antiferromagnet CsMnF3. The observed data were satisfactorily fitted to a theoretical model with two nearest-neighbour exchange constants, J12 = 0.134 ± 0.003 THz and J23 = 0.094 ± 0.0105 THz, and with one second-nearest-neighbour exchange constant, J35 = −0.0138 ± 0.003 THz. An effective anisotropy field of −2700 ± 900 Oe along the crystal c axis was also included in the model. This field constrains the spins to the basal plane of the crystal and calculations show that magnetic dipole–dipole interactions can account for its observed magnitude.
Mass splitting of charmed baryons by weight diagrams
Authors: Zadoo Tej K. , Ahmad Mubarak
Published: April 2011

Weight diagrams for 3/2+ charmed baryons are drawn. Sum rules are derived from same by using a modified version of the parallelogram law.
Asymptotic behaviour near past null infinity for scattering problems
Authors: Walker Martin
Published: April 2011

The following problem is treated: two particles move toward each other from infinity with equal but opposite velocities and finite impact parameter. Each particle is deflected by the field of the other. The particles recede, finally, back out to infinity. Electromagnetic and gravitational interactions between the particles are considered. It is shown, in both cases, that the use of retarded interactions, in an approximation scheme which begins with no interaction in flat space-time, guarantees the absence of incoming radiation. This result may be of relevance to the much more difficult problem of the description of bounded, isolated, gravitational systems.
Propagation of nonlinear electrostatic drift solitary waves in a collisionless plasma consisting of two ion species
Authors: Tagare S. G.
Published: April 2011

A modified two-dimensional Korteweg – de Vries equation for a collisionless plasma consisting of two distinct ionic species and isothermal electrons has been derived. The effect of concentration of light ions on the amplitude and the width of the drift solitary wave is examined for an argon plasma and a helium plasma with hydrogen ion impurities. Similarly the effect of concentration of negative ions on the amplitude of the drift solitary wave is examined and it is shown that when negative ions are present one gets the usual compressive drift solitary waves with positive amplitude as well as rarefactive drift solitary waves with negative amplitude depending on the negative ion concentration.
The electron binding energy effect on Compton scattering of X rays
Authors: Banerjee R. L.
Published: April 2011

In a series of papers on the measurements of the intensity of Compton scattering of X rays from crystalline samples as a function of scattering angle, this author has discovered a new effect. He has found that at the scattering angle for which the energy transfer between the scattered photon and the recoil electron is equal to the binding energy of an outer electron of the atoms in the sample, the intensity of Compton scattering shows a minimum. This effect is again detected in the present work in the case of a chromium single crystal and an interpretation of the effect is given on the basis of the theoretical work of Roulet and Nozières on the collective effects in the atoms.
Nonlinear resonant photoionization spectra of molecular iodine
Authors: Dalby F. W. , Petty-Sil Gena , Pryce M. H. L. , Tai C.
Published: April 2011

A simple, sensitive method of observing coherent multiphoton transitions by observation of subsequent photoionization is described.The method has been applied to a study of molecular iodine leading to two-photon excitation of a new Rydberg state of symmetry 1g with Te′ = 53 562.75 cm−1,Be′ = (0.04029) cm−1, and ωe′ = 241.41 cm−1.A theory for the process is outlined. A quantitative measure of the absolute intensity has been made. The ionization cross-section from the Rydberg level is ≤ 1.6 × 10−19 cm2.
Displacement of an electromagnetic beam upon external dielectric reflection
Authors: Wong Man , Reesor G. E. , Read L. Arthur A.
Published: April 2011

The sideways displacement of an electromagnetic beam upon external reflection from a dielectric has been investigated. The experimental results, using 3 cm microwaves, are compared to those predicted by a theory based on a plane wave approach. The experiment has been completed for both perpendicular and parallel polarization as a function of total propagation distance at several angles of incidence around 45°.
Proton spin relaxation in hydrogen–nitrogen mixtures: a test of the single relaxation time approximation
Authors: Kalechstein Wallace , Armstrong Robin L.
Published: April 2011

Accurate measurements of the concentration dependence of the longitudinal proton spin relaxation time in hydrogen–nitrogen mixtures at 300 K are presented. The data are taken at 39 MHz and at densities for which the short correlation time limit approximation is valid. The measurements provide definitive evidence of deviations from the single relaxation time approximation. The Bloom–Oppenheim two-level theory is used to explain the detailed concentration dependence of the data.