bluuebunny/crossref_metadata_2025 huggingface dataset:
Observation of Beam–Plasma Interaction in a Toroidal Plasma in a Large Electric Field
Authors: Strilchuk A. R. , Skarsgard H. M.
Published: April 2011

Intense bursts of microwave radiation are emitted from a toroidal argon plasma subjected to a large electric field applied parallel to a confining magnetic field. The radiation spectrum has been measured in the range 0.95 to 6 GHz. Peaks in the spectrum can be reasonably accounted for by the theory of beam–plasma interaction between a small group of energetic electrons in the discharge and the main plasma. This indicates that the energetic electron group is an identifiable beam rather than part of a long flat tail on the electron velocity distribution.
Ionic Conductivity of Rubidium Iodide Crystals
Authors: Chandra Suresh , Rolfe John
Published: April 2011

The ionic conductivity of pure and strontium-doped rubidium iodide crystals was measured as a function of temperature. Eight transport parameters were calculated from the conductivity results by a nonlinear regression computation. The values obtained for the transport parameters were: Schottky defect formation enthalpy hs = 2.1 eV, entropy ss = 0.5 × 10−3 eV/deg; positive-ion vacancy migration enthalpy Δh1 = 0.60 eV, entropy Δs1 = 0.14 × 10−3 eV/deg; negative-ion vacancy migration enthalpy Δh2 = 1.6 eV, entropy Δs2 = 0.13 × 10−3 eV/deg; association enthalpy of strontium ions and positive-ion vacancies χ = 0.58 eV, entropy η = 0.22 × 10−3 eV/deg. Rubidium carbonate was found to have a negligible solid solubility in rubidium iodide, so that conductivity measurements could not be made on anion-doped crystals. The negative-ion vacancy migration parameters are thus not as accurately determined as the other transport parameters.
Inelastic Scattering of High Energy Electrons by Helium
Authors: Ojha S. P. , Tiwari P. , Rai D. K.
Published: April 2011

Generalized oscillator strengths and the cross section for excitation of helium by electron impact have been calculated in the Born approximation. Transitions from the ground state to the n1P (n = 2 and 3) states have been considered. Highly accurate wave functions of the Hartree–Fock and "configuration–interaction" type have been used to represent the ground state. Approximate wave functions due to Messmer have been employed for the final states. The results are compared with other calculations and with experiment.
On the Production of s-Wave Pions in Threshold p + p → π + d
Authors: Pradhan H. C. , Singh Yogeshwar
Published: April 2011

Using a number of nonlocal, two-term, separable, nucleon–nucleon interactions and their phase-equivalent transforms, it is shown that the production of s-wave pions near the threshold in the reaction p + p → π+ + d is sensitive, not only to the D-state probability of the deuteron and the nonlocality of the interaction, but also to the off-shell behavior of the interaction. The reaction, therefore, cannot serve, in the context of simple two-term separable potentials, as an effective criterion to constrain the value of the D-state probability of the deuteron to better than the present range of 3–8%. Results are presented also for Reid soft-core local interaction where we find that the off-shell effects are constrained by the deuteron form factor.
A Method for Obtaining Parametrized Bands of Rutile VO2
Authors: Mitra T. K. , Chatterjee S. , Hyland G. J.
Published: April 2011

With the metallic phase of VO2 in view, a method of obtaining parametrized bands, originally due to Slater and Koster, is developed for rutile structures in general. Thirty-four unsymmetrized Bloch states arising from localized 3d, 4s, 4p vanadium orbitals and 2s, 2p oxygen orbitals are projected into symmetric states—by the standard projection operator technique—at various points of symmetry of the BZ. The secular determinant with respect to these symmetric states is then reduced, the degree of reduction depending on the point of symmetry. Typical results are quoted. The paper concludes with some preliminary remarks concerning the connection of the present work with the phenomenological approach of Goodenough based on crystal field theory. In particular the π-like hybrid levels which feature prominently in this latter work are tentatively identified.
Temperature Dependence of the Diffusivity–Mobility Ratio in Degenerate Semiconductors in the Presence of a Large Magnetic Field
Authors: Chakravarti A. N. , Parui D. P.
Published: April 2011

The diffusivity–mobility ratio in degenerate semiconductors in the presence of a large magnetic field is found to increase with increasing temperature at a rate which is dependent on temperature at relatively low temperatures. It is also found that, at any given temperature, the ratio is increased by the application of the field.
The Resonance Fluorescence Spectrum of Sulfur Dioxide
Authors: Brand J. C. D. , Humphrey D. R. , Douglas A. E. , Zanon I.
Published: April 2011

The 2100 Å line of Zn+ excites strong resonance fluorescence in sulfur dioxide gas. Vibrational analysis shows that the fluorescence bands form progressions of about 5 members in ν1, ν2, and ν3, singly and in combination. Although the occurrence of transitions to odd- and even-numbered levels of ν3 without discernable alternation in intensity is unexplained, the widespread activity of ν3 provides strong physical evidence for an unsymmetrical (Cs) structure in the upper state of the transition. Rotational analysis indicates that the transition moment is parallel, or nearly parallel, to the a axis and therefore that the upper electronic state of these transitions has B2(A′) orbital symmetry.
Three-Photon Annihilation of Ortho-Positronium in Argon Gas
Authors: Bird H. M. B. , Jones G.
Published: April 2011

Marked deviations from simple exponential decay are known to characterize the two-photon annihilation of positrons in the noble gases. In this experiment, a quadruple coincidence system was used to examine the detailed shape of three-photon positron lifetime spectra in argon. No deviation from a simple exponential was observed over the density range 2.57 to 33 amagat, except when a high electric field was applied. The ability to distinguish three-photon ortho-positronium annihilation from other modes of positron annihilation permitted, for the first time, a detailed investigation of the density dependence of the annihilation of ortho-positronium in a simple monatomic gas. Over the whole density range, the ortho-positronium annihilation rate was found to depend linearly on density, with a value of 7.15 ± 0.10 μs−1 for the vacuum rate of ortho-positronium annihilation and 0.250 ± 015 μs−1 amagat−1 for the quenching rate of positronium in argon. With a field of 125 V cm−1 amagat−1 (at 2.57 amagat), a deviation from simple exponential decay was observed, a deviation whose shape is shown to be consistent with an interpretation in terms of time-delayed enhanced positronium production from the equilibrium free positron population.
State–Space Formulation of Scattering with Application to Spherically Symmetrical Objects
Authors: Hizal Altunkan , Tosun Haluk
Published: April 2011

A new differential formulation of scattering from dielectric bodies is described. The problem is reduced to the solution of spatially varying state–space equations for the multipole coefficients of the scattered field. The equations are confined into the body, and the solution yields directly the scattering coefficient outside the body. The method is applied to spherically symmetrical objects. Numerical results are presented for plane wave scattering from Luneberg and Eaton lenses and a plasma-coated conducting sphere. The radiation properties of an electric and magnetic dipole antenna, respectively covered by a plasma and a dielectric layer, are studied. The numerical results show that the radiation of these antennas can be enhanced over the free-space radiation by adjusting the thickness and the density of the layer.
The 127° Electrostatic Analyzer: Performance as a Spectrometer
Authors: Bryce P. , Dalglish R. L. , Kelly J. C.
Published: April 2011

The basic design and performance characteristics of a 127° electrostatic analyzer are derived from an exact solution of the potential within a bounded two-dimensional cylindrical sector. The results are compared with those found from radial field theory, to show that transmission is nonsymmetric in both energy and incident angle about the 'tuning' and 'normal' values respectively. Except for normally incident particles the usual radial-field calibration equation cannot be relied upon unless the analyzer design is altered to minimize end aberrations. Modified beam entry conditions are given to optimize the performance of the analyzer.
Electronic Structure of the Transition Elements
Authors: Saxena K. M. S. , Fraga S.
Published: April 2011

Numerical Hartree–Fock functions have been determined for the ground states and first excited states of the configurations 3dN4s0 and 3dN4s2 for the negative ions, neutral atoms, and first four positive ions of all the transition elements. The validity of the approximation, embodied in the use of a single set of parameters determined from the ground state function of a configuration for the prediction of the spectroscopic levels arising from it, has been examined in detail in the case of Fe I, 3d64s2, where independent calculations have been carried out for all the excited states.
Nonlinear Surface Wave Driving by an Oscillating Electrode
Authors: Ionides G. N. , Curzon F. L.
Published: April 2011

The excitation of surface waves on an incompressible, conducting fluid by a moveable charged electrode is considered. The electrode is maintained at a constant potential V and oscillated vertically with an amplitude d. The amplitude of the surface waves (resonantly driven) is determined as a function of V, d, and D, the average elevation of the electrode above the equilibrium fluid surface. The results show that the waves can be rendered overstable. It is pointed out that this may be an important mechanism in the transfer of charge between droplets in rain clouds.
The Decay of 160Eu
Authors: D'Auria J. M. , Guy R. D. , Gujrathi S. C.
Published: April 2011

A spectroscopic study of the decay of 160Eu to the levels of 160Gd was performed with sources produced from the (n, p) reaction on both enriched and natural gadolinium targets. Employing both β and γ spectrometers, singly and in coincidence, a decay scheme is proposed with 8 levels in 160Gd populated up to an energy of 1997 keV. The half-life was measured to be 50 ± 10 s with a Qβ- deduced to be 3.9 ± 0.3 MeV. A second, unidentified component was observed with a half-life of 8.0 ± 1 min, along with 7 γ rays. The possibility of a two-proton quasiparticle state in 160Gd is discussed.
NMR Relaxation Studies of Ferroelectric Colemanite
Authors: Watton A. , Petch H. E. , Pintar M. M.
Published: April 2011

Proton spin–lattice relaxation of the Zeeman reservoir in the laboratory and rotating frames and of the dipolar reservoir have been studied in ferroelectric colemanite. These studies indicate the presence of two relaxation mechanisms which can be related to motions of the water molecules. The first, referred to as the flip mode and identified with 180° flips of the water molecules about their H—O—H bisectrices, is characterized by a correlation time and U-shaped relaxation minimum expected for a normal thermally activated process. The second, referred to as the jump mode and associated with a structural configuration change, produces a cusp-shaped dip in the relaxation over a very small temperature range in the vicinity of the phase transition. Above the transition temperature, the jump mode frequency is higher than the Larmor frequency and the relaxation behavior is that expected for two thermally activated processes in the white spectral region. However, in the vicinity of the phase transition, the water molecules are tightly coupled to the structure as a whole and the jump mode frequency is determined by the structural stability of the crystal. In this region its behavior is no longer that of a thermally activated process for an isolated molecular group and its frequency approaches zero critically near the phase transition.
Distribution of the Sum of Photocounts in Gaussian Light of any State of Coherence and Polarization
Authors: Zardecki Andrzej , Delisle Claude
Published: April 2011

The probability distribution of photoelectrons detected simultaneously at L different points of a photocathode is studied under the assumptions that the incident light is Gaussian with arbitrary state of coherence and polarization. The generating function is expressed as an infinite product of eigenvalues of a matrix integral equation, the kernel being the correlation matrix. The case of spectrally pure light beams is discussed in detail and the relation to previous work is given. The notion of polarizationally pure beams is introduced, for which the polarization state of light is independent of the spatial and temporal coherence. The generating function is then expressed in terms of eigenvalues of a simpler integral equation. An approximate distribution valid up to the second moment is derived.
Influence de la Structure Fine des Raies de l'Hélium sur les Mesures de Concentration d'Atomes Métastables par Absorption Optique
Authors: Rajotte Raymond
Published: April 2011

We have obtained an algebraic relation taking into account the fine structure of spectral lines in the calculation of metastable atom density. Typical numerical results show that at high optical absorption errors of the order of 100% will result if we neglect the fine structure of lines.
Lifetime of the 5s5p1P1 Level of Strontium
Authors: Dickie L. O. , Kelly F. M. , Koh T. K. , Mathur M. S. , Suk F. C.
Published: April 2011

The lifetime of the first excited singlet level, 5s5p1P1, of strontium has been measured using the Hanle resonance of the 5s21S0 – 5s5p1P1, 4607 Å, resonance line. The lifetime of the 5s5p1P1 level is 5.29 ± 0.10 ns and the oscillator strength of the 4607 Å line is 1.80 ± 0.03. These results are compared with previous measurements.
Cylindrical and Spherical Shear Waves in Nonhomogeneous Isotropic Viscoelastic Media
Authors: Moodie T. Bryant
Published: April 2011

This paper is concerned with the propagation of viscoelastic shear waves in nonhomogeneous isotropic media. Herein we develop formal methods of solving the linearized equations of viscoelastodynamics in two and three dimensions for nonhomogeneous Maxwell solids whose properties depend continuously on a single radial coordinate. These methods are developed for the linearized equations of motion formulated in terms of shear stresses, and are based on Cooper's and Reiss' extension to linear homogeneous viscoelastic media of the Karal–Keller technique. Shearing stesses are applied to the boundaries of cylindrical and spherical openings in the viscoelastic media, and formal asymptotic wave front expansions of the solutions are obtained. In both cases a modulated progressive wave that propagates with variable velocity is obtained. The modulation depends on the moduli of rigidity and viscosity, whereas the velocity depends only on the modulus of rigidity. When the viscosity parameter in our Maxwell element tends to infinity, the results reduce to the known results for nonhomogeneous elastic solids.
Electromagnetic Potential Between Nucleons
Authors: Kiang D. , Machida S. , Nogami Y.
Published: April 2011

Some confusion concerning the electromagnetic potential between two nucleons when their finite size is taken into account is clarified.
On the Incompleteness of E and H Modes in Wave Guides
Authors: Collin R. E.
Published: April 2011

It is shown that a field expansion in terms of E and H modes for an arbitrary current source in a wave guide is complete for points outside the source region but does not give the complete field within the source region in general. It is also shown how the expansion may be completed by the addition of an extra term of simple form.
Near Ultraviolet Absorption Spectra of cis and trans Acrolein and Acrolein-d1
Authors: Osborne G. A. , Ramsay D. A.
Published: April 2011

The absorption spectrum of acrolein-d1 (CH2=CH∙CDO) has been studied in the region 3900 to 4400 Å with path lengths and pressures up to 10 m atm and temperatures from 25 to 160 °C. This study provides additional information for the interpretation of the vibrational structure observed in the 3A″–1A′ (trans), 1A″–1A′ (cis), and 3A″–1A′ (cis) systems of acrolein, in addition to new information for acrolein-d1. Most of the features in these spectra are now assigned.
CO2 Laser-Induced Dissociation of SiF4 Molecules into Electronically Excited Fragments
Authors: Isenor N. R. , Merchant V. , Hallsworth R. S. , Richardson M. C.
Published: April 2011

Observation of the visible fluorescence of the SiF radical in SiF4 gas irradiated by the pulsed output of a CO2 laser leads to the conclusion that the molecules are dissociated into electronically excited fragments by the action of the intense laser field. A clear distinction is observed between the fluorescence produced through this process and that associated with thermalization of the incident energy.
Méthode RAM et Calcul des Fonctions d'Onde Moléculaires Diatomiques et des Facteurs d'Intensité Rotationnelle Tenant Compte du Spin Nucléaire
Authors: Féménias J. L. , Athénour C. , Stringat R.
Published: April 2011

Van Vleck's RAM method is used for calculating rotational line strengths in electric dipole transitions between electronic states of diatomic molecules arising from coupling cases which involve the nuclear spin.
Ionospheric Magnetic Field Measurements at Auroral Latitudes
Authors: Pendrel J. V. , Koehler J. A. , Kavadas A.
Published: April 2011

The magnetometer data from five sounding rocket flights launched from Fort Churchill under a variety of auroral conditions are discussed. The data have been interpreted in terms of model currents which would reproduce the observed magnetic field variations.It was found in some cases that the current systems inferred from the rocket magnetometer were too weak to account for the ground-based magnetometer observations. This suggests that ionospheric current systems must occupy a much larger spatial extent than has generally been assumed in the past.
Ultrasonic Wave Propagation in CdS Phonon Maser Structures
Authors: Vrba J. , Haering R. R.
Published: April 2011

An analysis of phonon maser action in CdS is given which includes the complications arising from the presence of off-axis ultrasonic waves. The treatment includes the angular variation of the velocity of sound and of the piezoelectric coupling constant and takes account of mode conversion at the cavity walls. Numerical results are given for CdS maser structures.
Spatially Forbidden Regions in the Aurora
Authors: Parsons N. R. , Thomas I. L.
Published: April 2011

Attention is drawn to regions within the luminous auroral emission observed near the equatorwards boundary to the auroral oval that appear to be forbidden. These dark holes of approximately nightglow intensity in an auroral background of some 1/2 to 1 kR, between λ3450and λ5200 Å, were seen to drift from "west" to "east" parallel to the L contour with speeds of around 2.5 km s−1.
Spectre Électronique de la Molécule LuH
Authors: Effantin Christiane , D'Incan Jean
Published: April 2011

Six new electronic band systems, assigned to LuH, have been excited between 5000 and 8000 Å in a Lu2Cb–Th–Cu hollow cathode filled with argon and traces of hydrogen. The molecular constants and the nature of the electronic states of this molecule are derived from their rotational analysis.
Dynamics of Step Heat Waves in Gases and Plasmas
Authors: Ahlborn B. , Strachan J. D.
Published: April 2011

General properties of step heat waves are explained using the "response plane" which has axes of final enthalpy and absorbed power. As examples of heat waves we discuss the time development of ionizing radiation fronts in interstellar H II clouds, compare the description of chemical reactions in the response plane and the pv diagram, determine the operation conditions of steady fusion reactions, explain the time history of decaying laser sparks, and survey possibilities of thermonuclear fusion with lasers. All such heat waves exhibit similar fluid behavior since these phenomena occur due to the absorption of some energy into the ambient medium.
Dynamic Measurements on a Pulsed Short Arc Driven by a Magnetic Field
Authors: Drouet Michel G. , Beaudet Rosario
Published: April 2011

Current and voltage measurements were performed on a short (3 mm) arc burning at atmospheric pressure in air and driven (100–200 ms−1) along two rail electrodes by a transverse magnetic field. The arc current was pulsed from a steady state value of 40 A to 200–1000 A in < 10 μs. Simultaneous measurements revealed the arc voltage to be constant. On the contrary, a stationary arc, subjected to the same current step, showed a simultaneous temporary increase of the arc voltage of 10–40 V. To facilitate the interpretation of the results, the motion of the arc was recorded using a fast streak camera. It was found that, after applying the current step, the velocity of the arc does not change instantaneously, but that the luminous plasma expands in the wake of the arc. An interpretation of the results is proposed; it is based on the assumption that in a moving arc, the distributions of the current and the conductance are not similar.
Asymmetric Nuclear Matter in Second-Order Perturbation Theory
Authors: Côté Jean , Rouben Benjamin , Pearson J. M.
Published: April 2011

The second-order perturbation theory of nuclear matter is extended to the case where the neutron and proton densities are different. The symmetry coefficients given by the force of Tabakin and that of de Tourreil and Sprung are computed in second order.
A New Method for the Calculation of Level Shifts of Autoionizing States of Atoms with Application to the 2s2p1,3P Autoionizing States of Two-Electron Atoms
Authors: Sharma C. S. , Bowtell G.
Published: April 2011

A new method for the calculation of level shifts of autoionizing states of atoms is developed. It is suggested that this method is simpler and yet more accurate and mathematically more rigorous than other methods previously used for such calculations. The claim is substantiated by both mathematical arguments and by actual application of the method to the 2s2p1,3P autoionizing states of two-electron atoms.
Magnetoelastic Interactions in the Rare Earth – Iron Cubic Laves Phase Compounds RFe2
Authors: Southern B. W.
Published: April 2011

Finite strain theory is used to obtain expressions for the change in various measured elastic constants as a function of applied magnetic field for cubic ferromagnets. Using available data on magnetic anisotropy and magnetostriction, estimates are given for the size of effects that may be expected to be observed in the rare earth – iron cubic Laves phase compounds RFe2 (R = Tb, Dy, Ho, Er, and Tm). The fractional changes in the measured elastic constants for transverse waves are expected to be as large as 10−2 at room temperature.
On the Order Dependence of the Electrical Resistivity of Binary Alloys
Authors: Wang K. P.
Published: April 2011

A simple model capable of studying the order dependence of the electrical resistivity of noble-metal and transition-metal alloys is proposed. The limit of this model and its connections to other models are discussed.
Fluctuating Flow and Heat Transfer From a Vertical Surface
Authors: Singh Punyatma , Chaturvedi M. C.
Published: April 2011

The laminar boundary layer on a vertical body, when the surface temperature oscillates in magnitude about a constant nonzero mean, is analyzed. The separate solutions for low and high frequency ranges are developed. It is found that for low frequencies the oscillatory component of the Nusselt number at the plate increases as the buoyancy effect increases. For very high frequencies, the temperature field is of the "shear-wave" type unaffected by the steady mean flow and indicates a phase lead of 45° in the Nusselt number over that of the surface temperature oscillations.
Equilibrium Spacing in a CsCl Slab
Authors: Huang C. C. , Grindlay J.
Published: April 2011

A point ion model of a CsCl slab with (0,0,1) faces is shown to have no equilibrium state.
Temperature, Trapping, and Mobility Effects in Light Intensity Modulated Photoconductivity
Authors: Tokarsky R. W. , Brodie D. E.
Published: April 2011

The basic theory of intensity modulated light techniques is extended to consider the effect of temperature on the amplitude response, and it is shown that this may be used to obtain trap energies and densities. It is demonstrated that the temperature variation method is more sensitive than the usual light intensity variation method. The effects of a light intensity (carrier density) dependent mobility on the photoresponse are investigated, and the results for three different possible trap distributions are discussed. These latter effects may be observed in their characteristic a.c. photoresponse.
Approach to Ionization Equilibrium and Atomic Collision Cross-Section Measurement in a Helium Shock Wave
Authors: Kalra S. P. , Measures R. M.
Published: April 2011

A theoretical and experimental study of the initial ionization phase of an ionizing helium shock wave has been accomplished. Ionization relaxation time and the electron density profile behind the shock translational front have been measured. Both of these parameters have strong dependence upon the atomic collisional excitation rate in the initial phase of the ionizing shock wave, and therefore, a comparison with theory led to an estimation of the atom–atom collisional excitation cross section. Theoretical predictions for the relaxation zone of the helium shock wave indicated only a weak coupling between the electron and atom temperature during the relaxation process. A plasma focus driven shock tube was used to create the appropriate helium shock waves. Simultaneous measurement of the relaxation time and the electron density profile was performed using a multipass Fabry–Perot laser interferometer. A close agreement between the theoretical and the experimental temporal electron density profile was obtained with our experimental conditions (pressure P∞ = 0.5–5 Torr, shock Mach number 16–26). The effective cross section for atom–atom excitation close to threshold is [Formula: see text].
On the Penetrability through Double-Hump Barriers in Nuclear Fission
Authors: Leboeuf J. N. , Sharma R. C.
Published: April 2011

An attempt is made to refine the JWKB approximated expression for penetrability through a double-hump fission barrier when classical turning points are closely situated.
The Use of Gaussian Approximations in Nuclear Calculations
Authors: Griffin R. E. , Volkov A. B. , Lassey K. R.
Published: April 2011

Gaussian approximations can be extremely useful in calculations involving deformed nuclei. In particular, Nilsson type wave functions of a deformed Saxon–Wood type single-particle potential can be evaluated extremely rapidly by using Gaussians to describe the potential. Furthermore, a single 6-Gaussian approximation to the Coulomb interaction can be used to calculate the Coulomb energy to an appropriate accuracy for both light and heavy nuclei.
Mutual Diffusion Coefficients for the Systems HD–N2 and HD–Ar at 1 atm Pressure and 300 K
Authors: Harris K. R. , Bell T. N.
Published: April 2011

Mutual diffusion coefficients, D12, have been measured as a function of concentration for the systems HD–N2 and HD–Ar at 1 atm pressure and 300 K. The data are compared with previously published measurements for the corresponding H2 and D2 containing systems. After the estimated uncertainties due to experimental error and impurities, and corrections due to quantum and mass effects are taken into account, the mass corrected diffusion coefficient, [Formula: see text], for each system is found to lie above those of the corresponding H2 and D2 systems by up to 2%. These effects are attributed to differences in the intermolecular potentials of H2, D2, and HD.
A Circular Plane-Mirror Laser Interferometer Containing an Angular-Limiting Device
Authors: Hill K. O. , Campbell C. K.
Published: April 2011

The integral equation is derived for the steady-state modal-field distributions in a circular plane-mirror laser interferometer containing a symmetrically positioned angular-limiting device. It is shown that this equation reduces to the corresponding Fox and Li formulation in the limit when the aperture is fully opened.
Etats de valence de NS dans le domaine 2250–3800 Å
Authors: Jenouvrier Alain , Pascat Bernard
Published: April 2011

Five red-degraded transitions, A2Δ–X2Π, G2Σ−–X2Π, H2Π–X2Π, I2Σ+–X2Π, and B2Π–X2Π of 14N32S, have been observed in the region 2250–3800 Å. The complete rotational analysis of these transitions leads to a coherent attribution of the electronic transitions and reveals many perturbations in the rotational structures. All the levels of the A2Δ state are perturbed and the perturbing state is presumably a [Formula: see text] state.The most important results are given in the tables of molecular constants. An energy level diagram and potential curves show the relative positions of the different observed states.
The Resonance Fluorescence and Absorption Spectrum of Nitrogen Dioxide
Authors: Brand J. C. D. , Hardwick J. L. , Pirkle R. J. , Seliskar C. J.
Published: April 2011

A krypton ion laser operating at 6470 Å excites strong resonance fluorescence in nitrogen dioxide gas. The fluorescence bands have "parallel" structure (ΔK = 0) and are assigned to the electronically allowed subsystem of a 2B2–2A1 electronic transition. A partial rotational analysis is given for the upper state of the fluorescence bands, and their relationship to the absorption spectrum in the region 6000–11 500 Å is discussed.
Etude des bandes ν4 et ν7 de CH2D2 vers 9.5 μ
Authors: Morillon-Chapey Mireille , Alamichel Claude
Published: April 2011

ν4 and ν7 CH2D2 rovibrationnal bands have been analyzed with a spectrometer, the separating power of which is 0.08 cm−1. These bands are connected by a strong Coriolis resonance with [Formula: see text] and a positive sign for the product ζ74a (∂μb/∂q4)(∂μc/∂q7). The standard deviation between observed and calculated wavenumbers over the 424 measured transitions is 0.036 cm−1.
Optical Absorption Spectra of KBr:Pb2+ Crystals
Authors: Chaney Robert E. , Jacobs P. W. M. , Tsuboi Taiju
Published: April 2011

The fundamental properties of the absorption spectra of KBr:Pb2+ crystals have been studied at various temperatures from the liquid helium range to room temperature. The observed absorption bands are assigned to the so-called A, B, C, and D' bands by analogy with the absorption bands of other s2-configuration ions in alkali halide crystals. The B, C, and D′ bands overlap but have been resolved into their components by nonlinear least squares analysis. A discussion is given of the energy separation between the B and C bands in Sn2+-, Tl+-, and Pb2+-doped alkali halide crystals.
Investigation of the 0− → 0+ and 0− → 2+ Beta Transitions in the Decay of 144Pr
Authors: Bosch H. E. , Behar M. , Cambiaggio M. C. , Bermudez G. Garcia , Szybisz L.
Published: April 2011

The first-forbidden beta transitions 0− → 0+ and 0− → 2+ from the decay of 144Pr were studied. The corresponding spectrum shape factors and end-point energies were determined by means of a simultaneous fit of the data on both beta spectra with a theoretical function. The contribution of the induced pseudotensor term has been investigated analyzing the available information on spectrum shape factors, angular correlation, and longitudinal polarization.The data corresponding to both transitions were handled simultaneously. The introduction of the induced pseudotensor term is not indispensable for the interpretation of the experimental data. Besides, the nuclear matrix element [Formula: see text] for the 0− → 0+ transition was determined.
Observation of Quasi-Coherent Electron Oscillations and Spatial Bunching in a Converging Beam–Plasma System
Authors: Schott L. , Silawatshananai C.
Published: April 2011

A spatially periodic modulation of the plasma density is observed which is attributed to nonlinear bunching of counterstreaming electron beams leading to locally enhanced ionization. Microwave bursts (~1–5 GHz) strongly polarized in the direction of the beams are detected. Nearly coherent oscillations are found at frequencies about one order of magnitude lower than the electron plasma frequency but above the ion plasma frequency. The oscillations can be described by a theoretical cold beam–cold plasma model which takes into account the finite size of the plasma. The experimental results are in qualitative agreement with this model. A negative voltage pulse of 500 V and ~10 μs duration is applied between two concentric cylindrical electrodes. The outer electrode, the cathode, consists of heated tungsten filaments; the inner one, the anode, is perforated. The electrons emitted by the filaments are accelerated into the space enclosed by the anode where a plasma of a density [Formula: see text] and an electron energy of 1.5–10 eV is formed in argon at a pressure of 5 × 10−4 Torr.
Theory of Intercollisional Interference Effects. IV. Does a Zero Minimum in Induced Absorption Imply the Proportionality of the Induced Dipole Moment to the Force?
Authors: Lewis J. Courtenay
Published: April 2011

We show that, within the limits of the theory of intercollisional interference effects developed for collision-induced absorption by a Lorentz gas in paper I of this series, an intercollisional interference minimum which goes precisely to zero implies that the induced dipole moment is exactly proportional to the intermolecular force.
Hartree–Fock Alpha Cluster Density Distributions in Light A = 4n Nuclei Using Density Dependent Effective Interactions
Authors: Lassey K. R. , Manning M. R. P. , Volkov A. B.
Published: April 2011

Hartree–Fock calculations have been performed for the A = 4n nuclei 12C to 40Ca, employing a selection of density dependent effective interactions. This selection consists of two density and momentum dependent delta function interactions, similar to the Skyrme interaction, and two density and momentum dependent finite range interactions whose radial forms are given as a sum of two Gaussian functions. A basis of single-particle axially deformed harmonic oscillator functions is used. Special emphasis is given to the study of the occurrence of alpha-particle type clustering in the density distributions of light A = 4n nuclei and the influence of the strength of the one-body spin–orbit field.
Perturbation Theory and the Triangular Well Potential
Authors: Smith W. R. , Henderson D. , Barker J. A.
Published: April 2011

Accurate calculations of the second order term in the free energy and the first order term in the radial distribution function in the Barker–Henderson (BH) perturbation theory are presented for the triangular well potential. The BH theory is found to be fully satisfactory for this system. Thus, the conclusions of Card and Walkley regarding the accuracy of the BH theory are erroneous.
Positron Annihilation Rate Variation in the Presence of Electric and Magnetic Fields
Authors: Srivastava M. P. , Grover P. S.
Published: April 2011

The variation of the positron annihilation rate λa in noble gases He, Ne, and Ar has been studied in the presence of an external applied magnetic field, when the electric field is kept constant. It is found that λa increases as the magnetic field is increased. In the case of Ar, the dependence is quite appreciable whereas in He and Ne it is comparatively smaller.
Plasma Waves in an Inhomogeneous Plasma Carrying a Current
Authors: Bhatnagar T. N. , Sharma S. R.
Published: April 2011

Wave propagation in a magnetoactive plasma carrying a constant current is considered for the case of uniform and nonuniform media having a weak density gradient. The effect of drift velocity and nonuniformity is examined in detail for the longitudinal electrokinetic wave and the low frequency helicon wave propagation.
Singular Points in the Impurity Induced Far Infrared Absorption in KI
Authors: Ward R. W. , Clayman B. P. , Timusk T.
Published: April 2011

Low temperature, high resolution measurements of the far infrared absorption due to Na+, Br− and Cl− substitutional impurities in KI are presented. The continuous spectra are dominated by sharp features, some of which can be related to Van Hove singularities in the phonon spectrum of KI. This is confirmed by comparing the experimental spectra with theoretical calculations using a relaxation model for the defect and a shell model based on neutron spectroscopy for the phonons. While excellent agreement between experiment and theory is found for KI:Na+, agreement is not as good for the other systems. The model cannot account for additional peaks seen in the Br− induced spectra and also fails to account for the apparent reversal of a singularity type seen in KI:Cl− spectra.
Total Cross Section and Stellar Reaction Rates for the 58Ni(p,γ)59Cu Reaction
Authors: Hall T. H. , Cameron J. M. , McCamis R. H. , Moss G. A.
Published: April 2011

Measurements have been made of the total cross section for the radiative capture of protons by 58Ni for proton energies from 1.4 to 4.8 MeV using activation techniques. The 1.301 MeV γ rays emitted in the decay of 59Ni* following the β+ decay of 59Cu were observed. This reaction is important in the later stages of stellar nucleosynthesis through its role in the particle rich e process, where it is believed to affect the final abundances of 58Ni, 59Cu, and 59Co produced in some supernovae explosions. From these, and renormalized earlier resonant strength measurements, stellar reaction rates are calculated for temperatures from 2 to 6 × 109 K and found to be lower by about a factor of two than those currently used in model calculations.
Effects of Different Flow Field Conditions on the High Power Transmission Properties of a Reentry Plasma
Authors: Papa Robert J. , Taylor Richard L.
Published: April 2011

A computer program for calculating the high power microwave transmission coefficients of a chemically seeded reentry plasma has been described in two previous reports. It has been explained how the computer code can be used to optimize the amount of high power that can be transmitted from a reentry vehicle. Using a half implicit – half explicit time integration scheme, the electron and ion transport equations coupled with Maxwell's equations are numerically integrated to determine the nonlinear reflection and transmission coefficients of a reentry plasma. Graphs are presented of the electron density profile and plane wave reflection and transmission coefficients corresponding to the flow field conditions of a blunt-nosed reentry vehicle. The nonlinear transmission effects are studied as a function of vehicle altitude, antenna location on the vehicle, incident power level, pulse length, pulse repetition frequency, and convective flow velocity. Good agreement is obtained between theoretical results and actual rocket flight data.
Isomultiplet Mass Differences
Authors: Isgur Nathan
Published: April 2011

A simple proposal is presented for understanding hadron isomultiplet mass differences as being the sum of two contributions: the elastic electromagnetic self energy and a part that may be visualized as a mass difference between the p and n quarks. The ensuing calculation, even in its crudest manifestation, leads to remarkable agreement with the observed pattern of mass differences in terms of a single parameter.
Proton Spin Relaxation Study of Order Fluctuations Above the Nematic–Isotropic Transition in the Liquid Crystal MBBA: II. Coherent and Incoherent Scattering
Authors: Dong Ronald Y. , Tomchuk E. , Bock E.
Published: April 2011

The proton spin–lattice relaxation time T1 was measured at 18 different Larmor frequencies in the isotropic phase of MBBA at a fixed temperature of 51 °C. The refined theory of Ghosh in the framework of the deGennes theory is used to give a consistent picture for interpreting data over the frequency range of 4 to 60 MHz. At both low and high Larmor frequencies, the critical order fluctuations in the isotropic phase of MBBA arise mainly from a coherent scattering term which is observed in light scattering experiments. At a frequency of around 10 MHz, the critical order fluctuations come from both coherent and incoherent scattering. The smaller incoherent scattering can be studied by NMR under suitable experimental conditions. The correlation times for the fluctuations in coherent and incoherent scattering are different. The present study also gives the spin relaxation rate due to molecular diffusion as a function of frequency at 51 °C. An alternative to the Harmon–Muller frequency dependence of (T1)diff. is suggested for MBBA.
Influences de l'énergie thermique et de la répartition d'énergie des électrons dans les mesures par impact électronique
Authors: Delage A. , Roy D. , Carette J.-D.
Published: April 2011

The influence of thermal energy of atoms and molecules and of the energy distribution of electrons on results obtained from electronic impact experiments are analyzed. Special attention is devoted to the width of the peaks found in the spectra of elastically and inelastically scattered electrons. Results are presented in the convenient form of tables, graphs, and a nomogram in order that they may be easily accessible to researchers in the field of electronic collisions. The method used to calculate the influences of the experimental factors has also been used in the case of resonant elastic scattering of electrons in helium. These experimental factors are the thermal energy of the particles of the target and the spread of the electron energy.
Effect of Biquadratic Exchange on Two Magnon States of Heisenberg Ferromagnets: Other Neighbor Exchange
Authors: Pink D. A. , Sachdeva Vijay
Published: April 2011

We have investigated the two magnon localized states of a one dimensional Heisenberg ferromagnet the Hamiltonian of which is made up of nearest neighbor and next nearest neighbor isotropic bilinear and biquadratic exchange terms, and a single ion anisotropy term. We have restricted our choice of parameters so that the ground state at T = 0 is the fully aligned ferromagnetic state and we have used the thermodynamic Green functions where the averages have been evaluated in the ground state so that our results are good for [Formula: see text]. We have evaluated the probabilities of finding two spin deviations a distance n apart when the system is in a localized state described by total wave vector q. We have (a) compared the effects of ferromagnetic and antiferromagnetic next nearest neighbor exchange, (b) found that localized modes can lie below or above the two free magnon band depending upon the sign and magnitude of the biquadratic exchange, (c) found that in certain cases two spin deviations appear to behave like objects interacting only via a soft core, and (d) found that modes can have a large single ion component when the single ion anisotropy is zero.
Vers une réduction des modèles d'atomes fortement ionisés?
Authors: Rozelot J. P. , Noëns J. G.
Published: April 2011

In numerous studies, in astrophysics for instance, the large number of energy levels belonging to a highly ionized atom becomes rapidly unwieldy; systems are hard to deal with and simplifying assumptions vary from one author to another, since it is difficult to know a priori which levels can be left out of consideration in the study. This often impairs the accuracy of the results. A technique is proposed for reducing the ion model, in terms of its configurations, without neglecting any level. This procedure is applied to the case of Fe+10; the populations of the five lower levels are obtained by solving a system of 10 equations although 89 levels are taken into consideration. [Translated by the Journal]
Mesure du temps de relaxation pré-émission des molécules en solution
Authors: Niyonizeye Gaétan , Daigle Réjean , Denariez-Roberge M. M.
Published: April 2011

Time between excitation and emission is measured for a solution of HITC in various solvants. A dependance of this time as a function of η1/3 is observed.
The Total and K Shell Photoelectric Cross Sections for 661.6 keV Gamma Rays
Authors: Gowda Ramakrishna , Sanjeevaiah B.
Published: April 2011

The total and K shell photoelectric cross sections at 145, 279.1, and 411.8 keV have been measured for different converter foils using the well-type plastic scintillation spectrometer. The results have been published elsewhere. Using the same method the total and K shell photoelectric cross sections in copper, zirconium, silver, tin, tantalum, gold, and lead at 661.6 keV have been measured and the results are compared with the available experimentally measured and theoretically predicted values. The results are found to be in good agreement with the theoretical values of Schmickley and Pratt and also of Scofield.
The Effect of an Applied Transverse Magnetic Field on the Flow Stress of Superconducting Lead
Authors: Hutchison T. S. , McBride S. L.
Published: April 2011

The intermediate state in type I superconductors of rod form subject to a transverse magnetic field is characterized by a laminar normal superconducting structure. This gives rise to temperature and field dependent minima in the thermal conductivity. The measured plastic flow stress of lead crystals under these conditions is shown to be field dependent and to be related to the thermal conductivity via the previously developed relation (σH − σS) = −AT ln (κH/κS).
Properties of a Lattice Gas Model for 3He–4He Mixtures I: Generation of High Temperature Series
Authors: Plischke M. , Elliott C. J.
Published: April 2011

The Cheng–Schick model is a quantum mechanical lattice fluid for 3He–4He mixtures which reduces in one limit to the spin 1/2 XY model and in the opposite limit to a special case of the Hubbard model. The method for generating high temperature series expansions of the thermodynamic properties of the model is described in some detail. Series expansions in the inverse temperature have been obtained to order 10 for the free energy and to order 8 for the fluctuation in the long range order both for arbitrary boson and fermion fugacities and arbitrary exchange constant ratios. In the following article (Plischke and Betts) the series are analyzed and the results are compared with experiment and with other theories for 3He–4He mixtures.
Microwave Spectra in the ν4 Vibrational State of Methyl Cyanide and Methyl Isocyanide and Their 15N Derivatives
Authors: Bauer A. , Godon M.
Published: April 2011

Four pure rotational transitions have been observed between 99 and 183 GHz for the ν4 vibrational state of CH3CN, CH3NC, and their 15N derivatives. The rotation and centrifugal distortion constants are given for the four molecules. A vibrational resonance effect is detected on the [Formula: see text] lines of CH3NC.
Laboratory Determination of the Frequencies of Possible Interstellar Lines of NO+
Authors: Alberti F. , Douglas A. E.
Published: April 2011

The A1Π–X1Σ emission bands of NO+ have been photographed at high dispersion and, from the measurements of these spectra, the frequencies of lines which are likely to be of astronomical significance have been determined. The (J = 1)–(J = 0) transition of the lowest vibrational level of the X1Σ state is found to lie at 119 187 ± 30 MHz. The constants of the A1Π and X1Σ states have been improved.
A Comment on the Effect of Nonorthonormality on Atomic Transition Probabilities
Authors: Nicolaides Cleanthes A. , Beck Donald R.
Published: April 2011

We point out that for certain transition probabilities in neutral atoms, the nonorthonormality between the basis sets of initial and final wave functions should be accounted for explicitly. However, for most transition probabilities in the ions and many in the neutrals, it appears that the explicit consideration of nonorthonormality is not necessary, a fact which reduces the magnitude of many body calculations of these quantities considerably.