bluuebunny/crossref_metadata_2025 huggingface dataset:
Splitting in the absorption spectrum produced by strong and two-photon resonant fields
Authors: Blouin A. , Denariez-Roberge M. M.
Published: April 2011

We demonstrate in the present article that it is possible to observe a two-photon resonance splitting by the use of probe fields coupled to one or both of the degenerate levels.
Monometric and bimetric theories of gravity
Authors: Rastall Peter
Published: April 2011

The conventional classification of theories of gravitation (flat spacetime, monometric, bimetric, etc.,) is ambiguous. We illustrate the difficulties by describing a class of theories in which the metric is a function of a flat metric and a covector field. The extent to which the flat metric is determined by the algebraic conditions and field equations is analyzed. The results resolve problems of uniqueness in some previously developed theories.
A re-examination of the role of magnetic field lines in electromagnetic induction
Authors: Boteler D. H.
Published: April 2011

By adopting a view of magnetic fields, originally proposed by Faraday, in which the magnetic field changes by a movement of field lines, it is shown that a changing magnetic field can be described by the relation [Formula: see text] where v is the velocity of the magnetic field lines. These field-line velocities are shown to be the same as material velocities in conditions of infinite magnetic Reynolds number. The "moving field-line" view provides a phenomenological model of a changing magnetic field that is useful in electromagnetic induction studies. It also allows for a unified view of electromagnetic induction in which all induced electric fields can be explained by the v × B force alone.
Electric and magnetic dyadic Green's functions of bounded regions
Authors: Hadidi A. , Hamid M.
Published: April 2011

The eigenvector-expansion method is applied to obtain the electromagnetic fields in a closed region of space in terms of volume integrals over the sources and surface integral of the tangential electric field over the boundary. The field expressions are written in a convenient dyadic form, and thus the appropriate electric and magnetic dyadic Green's functions in an infinite triple-series form are extracted. Finally, the general formulas for the Green's dyadics are specialized for the case of a circular cylindrical cavity for which the series is reduced to a double summation. This reduction reveals the discontinuous nature of the fields in the source region.
Temperature profile of a boundary-layer arc
Authors: Au S. , Smy P. R.
Published: April 2011

The interaction between an arc immersed in a high-speed gas flow and an adjacent plane surface has been studied experimentally. The high-speed flow is generated in a conventional pressure-driven shock tube and the arc is supplied by a charged capacitor bank.The thickness of the arc layer has been monitored using a streak camera, and it is found that the distance from the surface to the point of maximum brightness in the arc is, in fact, within about 30% of theoretical predictions. Microdensitometric analysis of the streak photographs together with the use of a simple power-law relationship between plasma luminosity and plasma temperature generate temperature profiles through the arc layer; again these are very similar to their theoretical counterparts.
Vibrational Raman spectra of HD in the critical region
Authors: Staniaszek P. , Clouter M. J. , Kiefte H.
Published: April 2011

Interferometric lineshape data have been obtained for the polarized Raman (Q branch) spectrum of HD in the critical region (Tc = 35.91 K). The temperature dependence of the spectrum was investigated along isochores corresponding to the critical density (ρc), 0.50ρc, and 2.3ρc. Spectra of the saturated liquid and vapor were also obtained down to minimum temperatures of 18.11 and 31.93 K, respectively. The observed variations in spectral width have been interpreted in terms of vibrational dephasing and a specific kind of critical broadening, which occurs in the vicinity of the critical point.
Photon wave-packet diffraction by slits and apertures
Authors: Xiaoan Zhou
Published: April 2011

The field theoretical method in the treatment of photon interference by D. F. Walls is generalized to deal with photon wave-packet diffraction by slits and apertures using the wave-packet reduction postulation. The general formulae for diffraction by one photon, n photons, and a coherent photon field are obtained. The explicit form of the wave packet of one or several photons is given.
Supersymmetry anomalies and analytic regularization
Authors: Lee H. C. , Ho-Kim Q. , Liu F. Q.
Published: April 2011

The method of analytic regularization in which the number of dimensions is not generalized is shown to preserve the supersymmetry identity relating the anomalies of the supersymmetry current, the trace of the energy–momentum tensor, and the divergence of the axial current at the one-loop level. Explicit counterterms needed for the identity to hold are constructed. The method preserves Dirac and all other tensor algebras in D = 4 space and renders the computation of anomalies straightforward and simple.
Solution of discrete modes for wave propagation along multiple conductor structures above a dissipative Earth
Authors: Bridges G. , Aboul-Atta O. , Shafai L.
Published: April 2011

The discrete propagating modes for an N-conductor transmission line located above a dissipative Earth are determined. The boundary-value problem is solved using a Fourier transform approach that results in a set of Sommerfeld-type integrals, whose accurate evaluation is shown to become imperative at higher frequencies. Because the integrand of one of the integrals exhibits a pair of first-order poles, a significantly different solution to the customary transmission line dispersion equations is obtained, and additional discrete modal solutions become mathematically feasible in the neighbourhood of the poles. An analytical expression is presented for the general evaluation of the multiple-conductor transmission line problem. A parametric study of the discrete propagating modes for typical single- and two-conductor systems is made and discussed. The validity of a simplified quasi-transverse-electromagnetic approach as well as a small-argument expansion are also presented.
Information storage in ferroelectrics: thermal fixing
Authors: Guibaly Fayez El
Published: April 2011

Techniques for rendering permanent volume-phase holograms stored in ferroelectric crystals are discussed. An analysis is developed for the thermal fixing technique. The analysis identifies a phenomenological parameter that indicates whether or not thermal fixing would be successful for a given crystal. The results are applied to explain experimental observations for thermal fixing of holograms in lithium niobate (LiNbO3) crystals.
Role of thermal conduction in the expansion of a plasma from a vacuum interface
Authors: Parfeniuk D. , Ng A. , Celliers P.
Published: April 2011

The effects of thermal conduction are examined for the expansion of a plasma from a vacuum interface using an analytic model based on well-known self-similar models of rarefaction waves. Conventional analysis of shock-unloading experiments uses an isotropic expansion model. However, thermal conduction introduces a characteristic time scale during which the flow is not self-similar. The significance of this time scale for experimental measurements is also discussed. The characteristic time is calculated for an aluminum plasma using theoretical equation-of-state and conductivity models.
Laser theory with natural inclusion of radiation loss: Density-operator approach
Authors: Liberato A. , Baseia B.
Published: April 2011

A recent result of a previous paper describing the field loss in an optical cavity in a natural way is applied to laser theory. The field loss, due to the transmitted beam light, and the field gain, now attributed to the presence of active atoms but previously attributed to two noninteracting mechanisms, are correctly added to provide the equation of motion for the density operator of the radiation field. The replacement of individual operators, which appear in the conventional treatment, with collective operators is a conceptual difference that emerges from the present approach.
Measurements and analysis of rototranslational absorption spectra of low density H2–Ar mixtures
Authors: Dore P. , Filabozzi A. , Birnbaum G.
Published: April 2011

We present new measurements of the rototranslational absorption of H2–Ar mixtures at 195 and 298 K. Measurements were made at densities as low as possible. The first accurate (5% error) rototranslational spectrum of the H2–Ar pair was thus derived. We performed a line-shape analysis of these spectra; as a result, we found a low-frequency component associated with an isotropic overlap induced dipole. We also found an important anisotropic overlap contribution associated with the dominant quadrupolar induction. Through a spectral-moment analysis we determined the intensity of isotropic (λ0 = 2.35 ± 0.15 × 10−3ea0) and anisotropic (λ1 = 0.9 ± 0.1 × 10−3ea0) overlap induced dipoles. The range of the isotropic overlap induced dipole was found to be ρ0 = (0.105 ± 0.010)σ, in very good agreement with the value 0.11 σ frequently assumed in the literature for the range of overlap induced dipoles. Our measurements and the results of our analysis were in good agreement with results of recent computations.
Emission spectra of common discharge excimer-laser transitions
Authors: McKee Terrence J.
Published: April 2011

Measured broadband laser emission spectra are provided for ArF, KrF, and XeCl excimer lasers along with a list of previous references to these spectra.
New apodizers that arbitrarily decrease sensitivity to defocusing or to the variation of spherical aberration
Authors: Boivin Richard
Published: April 2011

Two families of pupil amplitude filters, or apodizers, are devised for rotationally symmetric optical systems. One type of apodizer, pertaining to systems with circular pupils, arbitrarily reduces their sensitivity to the variation of primary spherical aberration, when this is combined with defocusing to optimally compensate for the aberration. The other type of apodizer, pertaining to systems with slit pupils, arbitrarily extends their depth of focus.
Evolution of radiating charged spheres in general relativity
Authors: Medina V. , Núñez L. , Rago H. , Patiño A.
Published: April 2011

A method reported by Herrera et al. is extended to study radiating, charged, fluid spheres. A heuristic assumption relating pressure, energy density, the radial velocity of matter, and the electric-charge distribution is introduced. This ansatz, together with matching the boundaries with those of the Reissner–Nordstrom–Vaidya solution, leads to a system of ordinary differential equations for quantities evaluated at the surface. The integration allows one to obtain the profile of the physical variables for any piece of material via the Einstein–Maxwell equations. As an example of the procedure, a particular model is worked out in some detail.
Memory effects in the two-level atomic model
Authors: Brinati J. R. , Pimentel B. M. , Mizrahi S. S. , de Oliveira S. A. Carias
Published: April 2011

Memory effects are quantitatively evaluated in a two-level atomic model interacting with a thermalized reservoir, and the transient behavior is analyzed. For this purpose we derive a generalized master equation from the Liouville equation and we obtain the solution (Green functions) in an almost white-noise approach. We verify that the occupation probabilities present an oscillatory behavior that is due to the structure of the memory kernel.
Continuous subgroups of the Galilei and Galilei–similitude groups
Authors: Gagnon L.
Published: April 2011

We classify all the subalgebras of the Galilei algebra g(3) into conjugacy classes under the associated group G(3) and under the Galilei–similitude group Gd(3), which includes a simultaneous time and space dilation. We also classify the subalgebras of gd(3) under Gd(3). All the classifications are given up to an isomorphism, and the results are summarized in normalized lists.
Effect of a quantizing magnetic field on the Einstein relation in bismuth
Authors: Mondal M. , Banik S. N. , Ghatak K. P.
Published: April 2011

An attempt is made to study the Einstein relation of the carriers in bismuth under magnetic quantization on the basis of the Abrikosov dispersion relation, which includes various types of anisotropics in the energy spectrum. It is found, taking spin and broadening into account, that the same ratio oscillates with the inverse quantizing magnetic field and increases with increasing carrier degeneracy respectively. In addition, the corresponding well-known result of parabolic energy bands is also obtained from the generalized expression as a special case.
Integrals involving the three-parameter Fermi function
Authors: Maung Khin Maung , Deutchman P. A. , Royalty W. D.
Published: April 2011

It is shown that a binomial expansion in evaluating integrals involving the two- and three-parameter Fermi or Woods–Saxon function is possible because of bounded convergence and integrability. New results involving analytic expressions with the three-parameter Fermi function for integrals encountered in evaluating the nuclear moments [Formula: see text],the generalized moments [Formula: see text], and the radial Fourier transforms are presented. Also as a new result, an expression for the radial Fourier transform of the square of the two-parameter Woods–Saxon density is obtained, and the solution for the three-parameter density is indicated.
Total-to-K-shell photoelectric cross-section ratios in some rare-earth and high-Z elements
Authors: Lingam S. Chandra , Babu K. Suresh , Kumar V. Prakash , Reddy D. V. Krishna
Published: April 2011

The total photoelectric cross-sections in the elements gadolinium, dysprosium, erbium, lutetium, tantalum, tungsten, gold, and lead have been obtained by using the normal transmission experiments, and the results are reported. Using these total photoelectric cross sections, we have found the K-shell photoelectric cross sections, the K-jump ratios, and the total-to-K-shell photoelectric cross-section ratios at the K edges for the above elements. These values are compared with the available theoretical and experimental values. The results are in good agreement with the Storm and Israel results and the Scofield theoretical values, within the limits of experimental uncertainties. Furthermore, the variation of the total-to-K-shell photoelectric cross-section ratio with energy and atomic number is discussed.
A fast radiation transport algorithm for planar laser-produced plasmas
Authors: Marchand R. , Birnboim A. , Capjack C. E. , Salzmann D.
Published: April 2011

Radiation transport in planar laser-produced plasma is considered. An approximate transport algorithm is presented in which the specific intensity is calculated recursively at any point in the plasma. Results obtained with this simple model are in excellent agreement with those of a more accurate transport calculation in which each zone in the plasma is coupled to every other one. The saving in computer time, when using the recursive scheme, can be more than one order of magnitude.
Thermal effects on ion-acoustic whistlers in the ionosphere in the presence of negative ions
Authors: Sur A. K.
Published: April 2011

In this paper, the thermal effects in the presence of negative ions are included in the evaluation of the group travel time of an ion-cyclotron whistler from its source to an observer in a satellite. The velocity distribution function and the relative wave amplitude of the magnetic field have been estimated theoretically from the cyclotron damping of the whistlers. Comparison of the results with those of Das et al. and Das and Sur shows that negative ions and thermal effects have important contributions to the propagation of whistlers in the ionosphere. An outline of possible applications is given for the study of space plasma problems.
Diffusion dépolarisée Rayleigh par des molécules anisotropes: calcul analytique des contributions propres, collisionnelles et croisées pour divers potentiels
Authors: Dumon B. , Berrue J. , Chave A. , Barreau A.
Published: April 2011

In a preceding paper, a new analytical calculation of the integrated Rayleigh light scattered intensities, taking into account the permanent anisotropy in the collisionnal polarizability tensor, has been developped. The contributions of orientational pair correlation collision induced light scattering and the cross term have been evaluated in the first order dipole induced dipole approximation, at low density in the center–center polarizability scheme. In this article, from these analytical expansions, we calculate contribution values in N2, CO2, Cl2, and O2 to the scattered intensities. The intermolecular potential is represented by a two (or three)-site Lennard–Jones model without (or with) a quadrupolar moment. We show that these new analytical calculations lead to important corrections of up to 30% for the cross term in O2, and that the potential choice plays an essential role. These results are compared with experimental data and to other studies.
Bremsstrahlung linear polarization
Authors: Bianco W. Del , Carignan M.
Published: April 2011

The dependence of the bremsstrahlung perpendicular and parallel triple differential cross sections and the linear polarization on the angles and energies of the incident and scattered electron and of the emitted gamma-ray has been studied in the high-energy small-angle hypothesis. The expression used for the bremsstrahlung triple differential cross section is valid in the Born approximation and for an unscreened Coulomb potential of the nucleus.
Silsbee rule in YBa2Cu3O7 ceramic superconductors
Authors: Zwartz E. G. , Judd B. A. , Batalla E. , Wright L. S. , MacDonald W. D.
Published: April 2011

The transport critical current density, Jc, and the ac susceptibility have been measured for 28 YBa2Cu3O7, ceramic samples. It is observed that a Silsbee-like rule relates Jc to the alternating magnetic fields at which the ceramics begin to show a reduced Meissner effect.
Spin-polarized hydrogen, deuterium, and tritium: II. Pressure and compressibility calculated by a lowest order constrained-variation method
Authors: Haugen Magne , Østgaard Erlend
Published: April 2011

The pressure and the compressibility of spin-polarized H↓, D↓, and T↓ are obtained from ground-state energies calculated by means of a modified variational lowest order constrained-variation method. The pressure and the compressibility are calculated or estimated from the dependence of the ground-state energy on density or molar volume, generally in a density region from 0 to 1.5σ−3 corresponding to a molar volume of more than 20 cm3/mol, where σ = 3.69 Å (1Å = 10−10 m); the calculations are done for five different two-body potentials. Theoretical results for the pressure are 54.1–57.9 atm for spin-polarized H↓ 18.4–23.4 atm for spin-plolarized D↓, and 5.6–12.9 atm for spin-polarized T↓ at a particle density of 0.50σ−3 or a molar volume of 60 cm3/mol (1 atm = 101 kPa). Theoretical results for the compressibility are 51 × 10−4 −54 × 10−4 atm−1 for spin-polarized H↓, 108 × 10−4 −120 × 10−4 atm−1 for spin-polarized D↓, and 162 × 10−4 −224 × 10−4 atm−1 for spin-polarized T↓ at a particle density of 0.50σ−3 for a molar volume of 60 cm3/mol. The relative agreement between results for different potentials is somewhat better for higher densities.
Operator regularization on the hypersphere
Authors: McKeon D. G. C.
Published: April 2011

Operator regularization has proved to be a viable way of computing radiative corrections that avoids both the insertion of a regulating parameter into the initial Lagrangian and the occurrence of explicit infinities at any stage of the calculation. We show how this regulating technique can be used in conjunction with field theories defined on an n + 1-dimensional hypersphere, which is the stereographic projection of n-dimensional Euclidean space. The radius of the hypersphere acts as an infrared cutoff, thus eliminating the need to insert a mass parameter to serve as an infrared regulator. This has the advantage of leaving conformai symmetry present in massless theories, intact. We illustrate our approach by considering [Formula: see text], massless Yang–Mills gauge theories and the two-dimensional nonlinear bosonic sigma model with torsion. In the last model, the lowest mode is used as an infrared cutoff.
Vacuum ultraviolet emissions of trifluoromethane following electron impact in the wavelength range 50–130 nm
Authors: Wang Shouye , McConkey J. W.
Published: April 2011

The dissociative excitation of CF3H by electron impact has been studied under single collision conditions for incident energies up to 600 eV. The emission spectrum in the wavelength range 50–130 nm shows many features arising from neutral and singly ionized fluorine and carbon fragments, as well as from neutral hydrogen atoms. Absolute cross sections for the observed features were measured at 200 eV incident energy, while the excitation functions of the most intense emissions were studied over the whole energy range. The threshold excitation of the hydrogen Lyman α line displays onsets at 18.4 and 34.0 eV, while that of the fluorine F I 95.5 nm feature shows only one onset at 33.0 eV. Possible dissociation channels are discussed.
Analysis of the structure of the surface local density of states at the Fermi level: an application of the surface Green function matching method
Authors: Baquero R. , Quiroga L. , Camacho A.
Published: April 2011

We use a tight-binding description of the bands of bulk vanadium to set a surface-band structure. We show that knowledge of the s–d charge transfer in the surface layer is very important to be able to reproduce the ferromagnetic behavior of the (100) vanadium surface. We use the surface Stoner criterion of Allan to determine the acceptable values for the s–d charge transfer. There is no full agreement between theory and experiment on the magnetic properties of (100) vanadium at present.
Static effects of intermediate-range forces on polytropic stars of index N = 1
Authors: Leon J. Ponce de
Published: April 2011

Recent investigations suggest the existence of fundamental intermediate-range forces. Most calculations of their effects have been carried out under the simplifying assumption of uniform density. In this paper the question of how nonuniformity in the density can alter these effects is discussed. It is shown that the effects of intermediate-range forces on the stellar mass and radius are insensitive to the shape of the matter density.
Excited state baryon masses in a quark–diquark model
Authors: Norbury John W.
Published: April 2011

The Lichtenberg diquark model is used to analyze the nucleon and isobar mass spectra using a spin-independent, nonrelativistic linear potential. Qualitative agreement with data is found, leading to the conclusion that the Lichtenberg diquark model, in its present form, is consistent with the experimental mass spectrum.
Spontaneously broken Lorentz symmetry: an alternative model
Authors: Bradfield Terry
Published: April 2011

A simple model that exhibits spontaneously broken D-dimensional Lorentz symmetry is investigated. By allowing the tensorial as well as the antisymmetric part of the torsion to develop a nonvanishing vacuum value, a hierarchy of broken symmetries is obtained in which some or all of the gauge fields may become massive.
The preparation and some properties of low resistivity Zn3P2 films prepared using a hot-wall deposition method
Authors: Haque A. , Brodie D. E.
Published: April 2011

Low resistivity (100 Ω cm) films of polycrystalline Zn3P2 have been prepared by a hot-wall technique. The films are made up of randomly oriented crystals about 5 μm across. Films from 4 to 30 μm thick have been studied and a range of deposition parameters have been investigated. Doping densities of 1016/cm3 were achieved and three-hole trapping levels (near 0.37, 0.42, and 0.77 eV) were detected in Schottky barrier devices fabricated using these films.
Intervalley kinetic energy terms in the effective mass equation: a one-dimensional analytical study
Authors: Resca Lorenzo
Published: April 2011

We show that a one-dimensional analytical study allows us to test and clarify the derivation, assumptions, and symmetry properties of the intervalley effective mass equation (IVEME). In particular, we show that the IVEME is consistent with a two-band case, and is in fact exact for a model that satisfies exactly all its assumptions. On the other hand, an alternative formulation in k-space that includes intervalley kinetic energy terms is consistent with a one-band case, provided that intra-valley kinetic energy terms are also calculated consistent with one band. We also show that the standard symmetry assumptions for both real space and k-space formulations are not actually exact, but are consistent with a "total symmetric" projection, or with taking spherical averages in a three-dimensional case.
Polar trajectories around a black hole in a magnetic field
Authors: Krori K. D. , Sarmah J. C.
Published: April 2011

In this paper, we present a study of the stable polar trajectories ([Formula: see text] = constant plane) of neutral test particles around a Schwarzschild black hole embedded in a magnetic field. We also show how the nature of these trajectories changes with the variation in the angular momentum of the test particle and the magnetic field parameter.
Photocorrosion of hydrogenated amorphous silicon: effect of the solvent
Authors: Savadogo O. , Yelon A.
Published: April 2011

The photocorrosion of amorphous hydrogenated silicon (a-Si:H) in different solvents was studied. Impedance measurements were performed under potentiostatic conditions. At each potential, the impedance Z(ω, V) was determined in the frequency range 5 Hz–100 kHz. The Z(ω, V) diagrams were analyzed and the corrosion sensitivity of the material in different electrolytes was determined. A correlation between electroactivity domain and ac impedance curves is proposed. A relationship is used to describe the anodic corrosion process in different solvents. The electrolyte that shows no oxide growth at the semiconductor – electrolyte interface was deduced.
A time-dependent spin density functional theory for the dynamical spin susceptibility
Authors: Liu K. L. , Vosko S. H.
Published: April 2011

Within the framework of the time-dependent spin density functional formalism, we study the dynamical spin susceptibility [Formula: see text] of a general system of interacting electrons in the presence of a static external scalar potential. Based on the stationary property of the action functional, a variational expression for the real part of [Formula: see text] is derived: [Formula: see text]. The result is valid for a general exchange-correlation (XC) action functional. In particular, the XC factor 1(q,ω) is manifestly dependent on q and ω. The imaginary part Im [Formula: see text] is then determined through the Kramers–Kronig relation. Practical approximations for the required XC kernel are also discussed
Neutron diffraction study of the structure of the antifluorite crystal (NH4)2PbCl6
Authors: Armstrong Robin L. , Lo Bryan , Powell Brian M.
Published: April 2011

A neutron diffraction study of the crystal structure of (NH4)2PbCl6 is presented. Data taken at 100 and 4.2 K support a previous contention that (NH4)2PbCl6 undergoes a ferrorotative structural phase transition at 80 K, from a cubic structure with space group [Formula: see text] to a trigonal structure with space group [Formula: see text]. The primary-order parameter is the rotation angle [Formula: see text] of the PbCl6 octahedron about a [111] axis of the cubic phase; [Formula: see text] is 3.1° at 4.2 K. A small lattice distortion and an (NH4)+ ion displacement along [111] also occur and represent secondary-order parameters.
Lithium intercalation in crystalline LixMoS2
Authors: Mulhern Peter J.
Published: April 2011

Highly crystalline LixMoS2 was synthesized, and the lithium content was electrochemically varied between x ~ 0 and x ~ 1. There were five different phases each with a different lithium content. The crystal lattices had small triclinic or monoclinic distortions from 1T-hexagonal symmetry. These discoveries contradict claims in the literature that crystalline MoS2 disproportionates when the lithium content exceeds 0.2.
The relaxation function of the spin van der Waals model in a weak magnetic field
Authors: Lee Y. K. , Kim I. M.
Published: April 2011

We consider the spin van der Waals model in a weak magnetic field. For this model we obtain the relaxation function by applying the perturbative method that was developed for the evaluation of the relaxation function represented as an infinite continued fraction. To show the applicability of the perturbative method, we make comparisons between an exact result and various degrees of approximation.
a-Si:H prepared by low-energy ion beam assisted reactive evaporation
Authors: Brodie D. E. , Zhang S. , Craigen D. C. , Audas R. D.
Published: April 2011

a-Si:H has been deposited using low-energy (~55 eV) ion beam assisted reactive evaporation. An ion beam formed in an ion source using silane as the feed-through gas is directed at the substrate during film deposition. For this a-Si:H deposited on substrates held at temperatures above 490 K, the resulting films have only the silicon monohydride bonding configuration observable by IR absorption. Small amounts of the silicon dihydride or polyhydride configurations may be present in samples made on substrates held near 395 K. Electrical conductivity, optical band gap and the total hydrogen concentration all exhibit a reduced dependence on the substrate temperature relative to that observed in samples made without the use of the ion beam. Dark to light (AM1) conductivity ratios typically exceed 103.
Energy inquiry
Authors: Light Gregory
Published: April 2011

Introduced in this article is the notion of "invisible energy," which is similar to the existing notion of dual mass. By introducing invisible energy, a "larger" universe is simultaneously constructed. Within this larger framework, more gravitational motions can be explained theoretically.
Finitely conducting transverse-aligned plane magnetohydrodynamic confluent flows
Authors: Labropulu F. , Chandna O. P.
Published: April 2011

An equivalent alternate formulation of the finitely conducting transverse-aligned plane flow is obtained. Study of flows when isocurls coincide with streamlines, isobars coincide with isovels and streamlines, and isovels coincide with isobars and isocurls, respectively, are given as examples of this new formulation.
Quantum effects near the liquid–vapour critical point
Authors: Bruyn John R. de , Balzarini David A.
Published: April 2011

We gather together a number of recent measurements of the coexistence curve and compressibility of fluids close to the critical point, and investigate the variation of the critical exponents and amplitudes as quantum effects become more important. We find that the universal critical exponents and amplitude ratios are the same for quantum fluids as for room-temperature fluids, as expected. Some of the nonuniversal critical amplitudes, however, show systematic variations as quantum effects become significant, in at least qualitative agreement with theoretical predictions.
Observation of reactive and unreactive scattering of Ar+(2P3/2) and Ar+(2P1/2) by at low energies
Authors: Howard Stephen , Wang Jaiming , Birkinshaw Keith , Futrell Jean
Published: April 2011

The crossed-beam method was used to investigate the charge-transfer reaction of Ar+(2P3/2, 1/2) with [Formula: see text]. The percentage of Ar+(2P1/2) in the ion beam could be varied between about 1 and 33% by varying the operating conditions of the high-pressure ion source. Reactive scattering of Ar+(2P3/2) demonstrates that several different electronic states of the [Formula: see text] product are populated. Evidence that the ground-state ion appears to be highly vibrationally excited (ν = 0–12) is shown. Unreactive scattering of a mixture of Ar+(2P3/2) and Ar+(2P1/2) at 0.85 eV shows that all accessable vibrational states of ground-state O2 are populated as well as the fine-structure transition of Ar+(2P3/2) to Ar+(2P1/2).
The silane isotopomers 29SiH4 and 30SiH4 constants of the ν2/ν4 dyad
Authors: Prinz H. , Kreiner W. A. , Pierre G.
Published: April 2011

The IR spectrum of two silane isotopomers containing 29Si and 30Si was investigated with CO2 laser side bands in the range between 877 and 954 cm−1 at a resolution of 2 × 10−5 cm−1. An analysis of the ν2 and (or) ν4 dyad has been performed, including data obtained by Henry and Valentin from a Fourier transform spectrum and sub-Doppler lines observed by Bordé (Rev. Cethedec-Ondes NS, 83(1), 1 (1983)) and Skrzypczak et al. (J. Mol. Spectrosc. 138, 311 (1989)). From the fit 41 vibration–rotation constants, tΩ(K,nΓ) of the ν2/ν4 Hamiltonian have been determined.
Realizations of generators of complex angular momentum
Authors: Bora Shuchi , Chandola H. C. , Rajput B. S.
Published: April 2011

We use the generators of complex angular momentum in complex c3 space and derive the realizations of the homogeneous Lorentz group for nonzero real mass, zero mass, and imaginary mass systems. We use the appropriate little group for different systems to calculate the modifications in the spin contribution to angular momentum and the unphysical continuous spin representations are shown to be eliminated. We diagonalize the helicity operator in c3 space and obtain the generators of complex angular-momentum operators, which are shown to lead, in a general manner, to the standard helicity representations of the Poincare group for timelike and spacelike systems.
Evidence for three-body forces in p–d breakup at 25 MeV?
Authors: Wango W. B. , Birchall J. , McKee J. S. C. , Svenne J. P.
Published: April 2011

Experimental data for deuteron breakup by protons in collinear geometry at 25.00 MeV are compared with the predictions of rigorous Faddeev calculations using the Paris potential and with those of the Doleschall code. The Paris potential significantly underdetermines the breakup cross section in collinear geometry. The explanation for this discrepancy is not entirely clear at this time.
Thermal neutron capture γ-ray spectrum of lanthanum
Authors: Islam M. A. , Kennett T. J. , Prestwich W. V.
Published: April 2011

The thermal neutron capture gamma rays from the reaction 139La(n, γ)140La were investigated using a pair spectrometer and the tangential facility at the McMaster University Nuclear Reactor. A large number of previously unreported transitions have been observed from which details of the 140La structure are inferred. The level density is found to be consistent with a statistical model encompassing nuclear temperature. The reduced E1 strength function of 140La was found to be (1.4 ± 0.4) × 10−9 MeV−3. The giant dipole resonance model seems to overestimate the E1 strength in this nucleus. The separation energy of 140La is found to be 5161.00 ± 0.05 keV.
Investigation of the rovibrational levels of the B3Πg state of 14N2 molecule above the dissociation limit N(4S) + N(4S) by Fourier transform spectrometry
Authors: Roux F. , Michaud F.
Published: April 2011

Rotational analyses of vibrational levels of the B3Πg state, located above the dissociation threshold N(4S) + N(4S) were performed from a high-resolution emission spectrum recorded by Fourier transform spectrometry. Strong intensity perturbations were observed in the B3Πg vibrational levels ν′ = 13, 14, and 15.
Some remarks on the eigenvalue spectrum of a large symmetric Wigner random-sign matrix
Authors: Jones Raymund C. , Dhesi Gurjeet S.
Published: April 2011

The replica method is used to calculate the averaged eigenvalue spectrum as N → ∞, of the ensemble of Wigner random-sign real symmetric N × N matrices. Results are presented for the cases where the individual matrix elements have a mean value of zero and also where the mean value of the individual matrix elements has a finite nonzero value. It is shown that the replica method provides a straightforward framework within which it is possible to verify the Wigner conjecture that any reasonably well-behaved distribution of matrix elements must lead to the well-known semicircular averaged eigenvalue spectrum of the Gaussian orthogonal ensemble of random matrices. Some numerical simulations of the averaged eigenvalue spectrum of these random-sign matrices are presented and they lend support to the prediction that if the individual matrix elements have sufficiently large a mean value, then a single eigenvalue will split off from the main semicircular band of eigenvalues.
Inversion of cosmogenic-nuclide data from iron meteorites
Authors: Pearce S. J. , Russell R. D.
Published: April 2011

The interpretation of the observed abundances of cosmogenic nuclides in meteorites involves two considerations, namely, the cosmic-ray-exposure ages and the past behaviour of the particle flux. Traditional methods of analysis do not have the mathematical structure to simultaneously deal with both questions in a convenient and rigorous fashion. Reformulating this problem within the framework of inverse theory allows for a new and powerful perspective: it enables us to make simultaneous, self-consistent estimates of the flux prehistory and the exposure ages, and of their uncertainties. In this paper we have focussed on inversions that would, if possible, give constant-flux prehistories, and, in any case, would give the flattest model in a least-squares sense. This allows us to show by rigorous examination that the available data are inconsistent with the assumption that the flux was constant over a period of 109 years. While this is not an original conclusion, it is reached here by a much more direct analysis, and we are able to make a defensible estimate for the change in the 109 years. The analysis also yields new estimates of the exposure ages that are consistent with the time-varying flux. That is, one does not need to presuppose any particular functional form for the flux. The application of inverse theory to such problems also makes available additional benefits that have been widely recognized in geophysical analysis. For example, it forces one to explicitly acknowledge the inherent assumptions, it provides quantitative estimates of the uncertainty of the results, and it provides a means of anticipating the value of new experimental data. We have based our demonstration on published data from four individual iron meteorites, since these data apparently provide a self-consistent set. Smoothed estimates are derived of the long-term prehistory of the particle flux at similar depths within these bodies (1000 kg m−2 as inferred from the cosmogenic nuclides 21Ne and 40K). With our preferred choice for the present value of the particle flux, the results independently support a model in which the magnitude of the particle flux 109 years ago was about 40% less than the present value; the individual estimates for the four meteorites of the ratio of the present flux to the flux 109 years ago are 1.75 (Mount Ayliff), 1.66 (Yardymly), 1.64 (Williamstown), and 1.72 (Carbo). The exposure ages consistent with this history are smaller, by some 10–20%, than previous estimates. One can choose a smaller value for the present particle flux to bring the ages into agreement with previously estimates values, but then a substantially larger change in flux with time is required. Thus our analysis provides a sophisticated test of the possibility of a constant-flux model.
Interference spectra in a two-level atom
Authors: Mavroyannis Constantine
Published: April 2011

We have considered the interference spectra arising from the competition between a spontaneous process and one induced by a laser field in a two-level atom. Expressions for the spectral functions have been derived describing the spectra of the excited and ground states of the atom in the low- and high-intensity limit of the laser field. For the excited-state spectra in the low-intensity limit, the frequency profiles of the two peaks, which arise from the spontaneous and the induced processes, cancel each other out completely near the center of the line, while for the ground state the induced process dominates. For finite values of the detuning, the spectra of the excited state consist of two peaks, which have positive and negative frequency profiles, respectively. The computed spectra have been graphically presented and discussed. In the high-intensity limit, the dynamic Stark effect dominates the spectra of the excited and ground states of the atom. Expressions for the correlation functions have been derived that describe the emission or the absorption of a laser photon at two different times. The derived expressions for the corresponding delay functions in the low- and high-intensity limits have been found to be identical to those recently proposed in the literature. The laser field has been treated as a classical as well as a quantized entity.
Electrochemical effects in metal1 – a-Si:H – metal2 structures
Authors: Paquin Louis , Leclerc Gervais , Wertheimer M. R.
Published: April 2011

In the course of studying microwave plasma-deposited a-Si:H, some M1 – a-Si:H – M2 structures (where M1, and M2 represent dissimilar metals) exhibited a behavior similar to that of galvanic cells. For many pairs of metallic electrodes we have observed, in the dark, an open-circuit voltage (Voc) and a short-circuit current (Isc) that were stable over a period of several months. Such effects have been variously reported for M1–polymer–M2 cells, where no doubt remains as to their electrochemical origin. We describe here the observed phenomena, along with results from chemical profiling (elastic recoil detection analysis and Auger electron spectroscopy) studies, aging characterization by Fourier transform infrared spectroscopy, morphological studies by scanning transmission electron microscopy, low-frequency permittivity measurements, and I–V behavior in the dark and under illumination, and we interpret these results in terms of electrochemical reactions.
Analysis of dyad – dyad transitions of 12CH4 and 13CH4
Authors: Roche C. , Champion J. P.
Published: April 2011

This work is a refinement of the (0100) and (0001) state description for both isotopes 12CH4 and 13CH4. We introduce recently observed dyad–dyad lines in addition to "pure rotational" and infrared transitions in a simultaneous fit of the ground-and upper-state parameters. Using a sixth-order-reduced Hamiltonian, significant improvements are achieved for the upper-state parameters that were previously retrieved from infrared transitions only. As a result, substantially more accurate predictions of the dyad – dyad spectrum of both isotopes are reported in the frequency range 0–300 GHz with a strength greater than 10−11 cm−2 atm−1 at 296 K.
Photoproduction of W bosons as a test of the standard model
Authors: Samuel Mark A. , Kalman C. , Frank M. , Hamzaoui C. , Li Guowen
Published: April 2011

The photoproduction of W bosons is proposed as a means of testing the standard model. In particular, the radiation amplitude zero, which may occur in this process, provides a sensitive measure of the magnetic moment of the W bosons. Such experiments, using colliding beams, are feasible with present-day accelerators.
Harmonic-oscillator transformation coefficients
Authors: Davies K. T. R. , Krieger S. J.
Published: April 2011

An elegant but simple formalism is used to construct the three-dimensional harmonic oscillator in Cartesian, cylindrical, and spherical coordinates. Then, transformation coefficients between these representations are derived using straightforward angular-momentum and combinatorial algebra. Such coefficients, which should be applicable to many fields of physics, have been particularly useful in studies of nuclear shapes.
Non-Newtonian-flow formation in Couette motion in magnetohydrodynamics with time-varying suction
Authors: Eldabe Nabil T. , Hassan Ahmed A. A.
Published: April 2011

This paper is an analysis of an incompressible flow of electrically conducting non-Newtonian fluid between two infinite parallel walls one of them moving with a uniform velocity under the action of a transverse magnetic field. The moving wall is subjected to a suction whose magnitude oscillates with respect to time over a constant mean. In our analysis we are taking into account the induced magnetic field; a matter that is neglected by the majority of the previous work. The main results show that the effect of the viscoelasticity of the fluid is to decrease both the flow and the induced magnetic field.
Study of the radioactive decays of 140Ba and 140La
Authors: Chand Bakhshish , Goswamy Jatinder , Mehta Devinder , Singh Nirmal , Trehan P. N.
Published: April 2011

The intensities of X rays and γ rays from the decays of 140Ba and 140La were measured precisely using Si(Li) and HPGe detectors. The L X-ray intensities in 140Ba decay are reported for the first time. The conversion electrons from these decays are investigated using a mini-orange electron spectrometer. The electron intensities for the (M + N.) conversion of 329, 487, 1596, and 1903 keV transitions in 140Ce were measured for the first time. From the present conversion-electron and γ-ray intensities, the conversion coefficients for various transitions in 140La and 140Ce were determined. Also, the γ–γ directional correlations for 15 cascades in,140Ce were studied using a HPGe–HPGe detector coincidence setup (time resolution = 7 ns). The 109–(329)– 487, 131–242, and 131–266 keV cascades in 140Ce were studied for the first time. The multipole mixing ratios for the 109, 131, 242, 266, 329, 432, 487, 751, 816, 868, 919, 925, and 951 keV transitions in 140Ce are deduced from the present directional correlation and conversion-coefficient measurements.
The effects of electron bombardment on vacuum-deposited amorphous germanium films
Authors: Johnson G. W. , Brodie D. E.
Published: April 2011

Low-energy electron irradiation was used to inhibit crystallite nucleation in a range of substrate temperatures (473–513 K) where crystallite formation would normally be observed. The properties of the amorphous phase obtained closely match the published results for high-temperature annealed (up to 723 K) amorphous germanium films in the precrystallization regime rather than those for amorphous germanium films obtained by annealing them to 513 K. It is shown that the properties of annealed amorphous germanium films are independent of a range of deposition conditions when pure (water free) films are deposited.
Synthesis of line-source feeds for conical reflectors and their performance using dipole arrays
Authors: Eid D. A. M. , Shafai L.
Published: April 2011

The matched feed concept is used to determine the electrical characteristics of a line-source feed for conical-reflector antennas. A linearly polarized plane wave incident on the reflector is used to determine the field distribution along and in the vicinity of the focal axis of the reflector. The co-polar, cross-polar, and axial field components are determined and their dependence on reflector size, cone angle, and radial distance is studied. The results indicate that for a line source of finite diameter, its surface field distribution must contain other field components to generate a linearly polarized far field. Based on the matched feed concept, line sources in the form of simple dipole arrays are proposed and the conical-reflector radiation patterns are computed. The dependence of the pattern characteristics, such as the polarization, efficiency, and side-lobe levels on the dipole excitations is studied and discussed.