bluuebunny/crossref_metadata_2025 huggingface dataset:
Powerful Nanosecond Pulses by Stable Passive Mode-Locking of TEA CO2 Lasers
Authors: Fortin R. , Rheault F. , Gilbert J. , Blanchard M. , Lachambre J. L.
Published: April 2011

Passive mode-locking of a double-discharge TEA CO2 laser using SF6 as bleachable absorber has been achieved on several rot–vib transitions of the 00°1–10°0 band. Stable pulses shorter than 2 ns and having peak powers in the 100–200 MW range have been regularly obtained. The experimental conditions and operating characteristics of the laser required to achieve stability are described.
The Electronic Spectrum of HF. I. The B1Σ+–X1Σ+ Band System
Authors: Lonardo G. Di , Douglas A. E.
Published: April 2011

The electronic emission and absorption spectrum of HF has been photographed at high resolution with a 10 m grating spectrograph. The emission, which extends from 2670 to 1480 Å, consists entirely of bands of the B1Σ+–X1Σ+ (previously denoted as the V1Σ+–X1Σ+)system. From the analysis of 51 bands of the emission spectrum, constants of the vibrational levels of the X state from ν = 7 and 19 and of the B state from ν = 0 to 10 have been determined. The dissociation energy of HF has been found to be D0(HF) = 47 333 ± 60 cm−1. In the absorption spectrum, 56 bands of the B–X system have been identified. Vibrational levels of the B state between ν = 14 and 26 were found to be well behaved and readily analyzed, but levels between ν = 26 and 73 were found to be highly perturbed. Rydberg–Klein–Rees potential curves have been calculated for the B and X states and it is shown that at large internuclear distances the bonding of the B state is almost entirely ionic.
Magnetooptical Properties of GaSe near the Band Gap
Authors: Brebner J. L.
Published: April 2011

Optical transmission measurements have been made on thin high quality crystals of GaSe in fields of up to 93.5 kG. The fields were aligned parallel and perpendicular to the ψ axis. The symmetries of the valence and conduction bands are discussed in the light of the zero field data, and subsequently the behavior of the excitons in the magnetic field is discussed. Values for the effective masses of holes and electrons normal to the ψ axis are determined to be 0.45m0 and 0.20m0 respectively. The values of the g factors parallel and perpendicular to the ψ axis are also deduced.
Admittance of a Spherical Probe in a Warm Electron–Ion Plasma
Authors: Homonick B. , Balmain K. G.
Published: April 2011

Two-fluid, scalar-pressure theory with an absorptive boundary condition is used to calculate the input admittance of a spherical probe in a warm electron–ion plasma. In addition to the usual resonances at the electron plasma frequency and at the sheath–plasma "series resonance" frequency, the theory predicts a rather broad resonance just below the ion plasma frequency. In the zero-frequency limit, the predicted input conductance is essentially the slope of a Langmuir probe current–voltage curve. The prediction of an ion plasma resonance is in qualitative agreement with experiments reported elsewhere.
Ambipolar Drift, Deformation, and Diffusion of a Plasma in a Magnetic Field
Authors: Monroe Richard L.
Published: April 2011

The theoretical problem of a weakly ionized, constant temperature, three particle plasma in an externally generated magnetic field is reformulated by transforming the set of 14 macroscopic plasma equations (continuity and momentum equations for ions and electrons plus Maxwell's equations) in 14 unknowns (ion and electron number densities and velocities plus the effective electric and magnetic fields) into an equivalent set of 4 integral equations in 4 unknowns. In the course of this transformation, it is shown that the plasma behavior can be interpreted in terms of three ambipolar processes : drift, deformation, and diffusion. Plasma diffusion is characterized by two diffusion coefficients : the usual Schottky formula applying in the direction parallel to the effective magnetic field and a new expression for the ambipolar transverse diffusion coefficient applying in directions perpendicular to the effective magnetic field. The new ambipolar coefficient differs markedly from the familiar ambipolar coefficient associated with the names of Bickerton, Lehnert, Holway, Allis, and Buchsbaum; and, in general, it gives values for the transverse diffusion coefficient which are two orders of magnitude larger than those given by the latter. It is concluded that ambipolar diffusion can produce a transverse diffusion coefficient large enough to account for the diffusion rates measured by Bohm, Burhop, Massey, and Williams in argon arc discharges.
Raman and Infrared Spectra of Na2SeO3, NaHSeO3, H2SeO3, and NaH3(SeO3)2
Authors: Torrie B. H.
Published: April 2011

The Raman and infrared spectra of four selenite compounds have been measured and compared to the Raman spectra of SeO32−, HSeO3−, and H2SeO3 in solution obtained previously by Walrafen. A. general force field has been used to obtain force constants for the selenite ions and to examine the effect of varying the stretching force constants. The results are discussed in relation to phase transitions in Na(H1−xDx)3(SeO3)2 which have been associated with ordering of the hydrogen atoms.
The a4Σ−–X2Π Electronic Transition of SiF
Authors: Martin R. W. , Merer A. J.
Published: April 2011

The a4Σ−–X2Π transition of SiF at 3360 Å has been reinvestigated at high dispersion. Our new rotational line assignments show that the energy levels of the 4Σ state, which is very close to case (b) coupling, can be fitted with one rho-type doubling parameter (γ) rather than the two proposed by Hougen to account for Verma's previous results. The relative intensities of the branches have been interpreted in terms of two transition moments, whose ratio shows that the intensity of the a–X system comes mainly from the so far uncharacterized σπ22Σ+–X2Π transition. 'Equilibrium' molecular constants for the a4Σ− state have been derived from analysis of the overlapping sequence bands.
Analyse de la Transition 2Σ(bβJ) → 2Σ(bβS) du Radical LuO
Authors: Bacis R. , Bernard A.
Published: April 2011

The violet system of LuO is interpreted as a 2Σ(bβJ) → 2Σ(bβS) transition.This assumption accounts for the broadening of the lines of some branches, and the irregularities in the intensity ratios between the G = 3 and 4 components of a line are explained in terms of a bβJ tendency of the ground state.The detailed study of the (0–0) band allowed the accurate calculation of the fundamental state constants, as well as the perturbed constants of the excited state by taking into consideration only the unshifted lines. With the help of a novel computer program, it is shown that the deperturbed constants don't differ appreciably from the perturbed ones. The value of the perturbation matrix element and of the rotational constant of the perturbing state are obtained. The nature of the latter is not determined with certainty; however, it seems that most probably a 2Σ–2Π1/2 type interaction is involved. The intensity differences between the lines of the R and P branches corresponding to the same excited sublevel may be explained on the basis of this hypothesis.
Some Rationale for the Unusual Behavior of the Dielectric Constant of Cu2O
Authors: Weichman F. L.
Published: April 2011

The very low frequency dielectric constant in Cu2O varies over wide limits and is highly temperature dependent. At sufficiently low temperatures the dielectric constant for all samples reduces to the high frequency value of about 7.5. Small variations in the high frequency value are easily explained as being due to the known presence of copper crystals embedded in the semiconducting material. The low frequency and temperature variations will be related to the variation in the depletion layer formed around each copper inclusion. Calculations are based on highly oversimplified size, shape, and distribution of the copper inclusions.
Intensity of the Pressure-Induced Fundamental Infrared Band of Gaseous Chlorine
Authors: Wong P. T. T. , Whalley E.
Published: April 2011

The integrated intensity of the pressure-induced fundamental band of gaseous chlorine measured by Winkel, Hunt, and Clouter is about 5 times that calculated assuming that the transition moment arises from the oscillation of quadrupole-induced dipole moments. This provides good evidence that valence-type interaction between gaseous chlorine molecules occurs.
Collisional Depolarization of Mercury Resonance Radiation
Authors: Phaneuf R. A. , Pitre J. , Hammond K. , Krause L.
Published: April 2011

The depolarization of mercury resonance radiation (2537 Å), induced in collisions of Hg(63p1) atoms with various buffer gases, has been investigated using the method of delayed coincidences. The experiments yielded the following depolarization cross sections. Hg–He, 37.8 Å2; Hg–Ne, 43.5 Å2; Hg–Ar, 72.9 Å2; Hg–Kr, 101 Å2; Hg–Xe, 144 Å2; Hg–N2, 120 Å2.
A Method for Numerical Integration of Time-Dependent Einstein Equations
Authors: Pachner J. , Teshima R.
Published: April 2011

A method for the numerical computation of the initial data and for the numerical integration of the exact Einstein field equations is described for the case of a rotating incoherent matter with axial symmetry. The results of the integration show that the method gives reliable results.
The Observation of a Displacive Phase Transition in (NH4)2PtBr6
Authors: Wiszniewska Maria , Armstrong Robin L.
Published: April 2011

Measurements of the 79Br nuclear quadrupole resonance frequency and spin–lattice relaxation time in a polycrystalline sample of (NH4)2PtBr6 from 4 to 450 K are reported. The frequency data indicate the occurrence of a structural phase transition at 58 K. The spin–lattice relaxation time data exhibit a distinct minimum, also at 58 K. The data are discussed in terms of a model previously introduced to account for phase transitions from cubic to tetragonal symmetry in R2MX6 compounds. A point charge calculation provides an explanation of the observed frequency splitting in terms of the alteration in the neighboring ion contribution to the electric field gradient at the 79Br nuclear sites. This alteration results from a small distortion of the cages defined by the NH4 ions and an accompanying rotation of the PtBr6 octahedra situated within these cages. The temperature dependences of two different average rotary lattice mode frequencies are deduced; in each case the observed behavior supports the hypothesis that it is the rotary lattice mode which softens thereby bringing about the change in structure.
Null Correlation Method for Estimation of the Primary Energies of Cosmic Ray Jets
Authors: Streitmatter Robert E.
Published: April 2011

A new method for estimating the center of mass of high energy cosmic ray interactions is introduced and tested with a simple Monte Carlo model and a small number of cloud chamber jets.
Structures dans l'Emission Photonique de He Provoquée par Bombardement d'Electrons Monocinétiques dans la Région de 60 eV
Authors: Marchand Pierre D.
Published: April 2011

By measuring the photon intensity emitted by He excited by electron impact in the 60 eV region as a function of the electron energy, with an apparatus capable of excellent signal to noise ratio and energy resolution, several structures have been observed, some being entirely new and attributed to levels of the negative He− ion.
Density and Temperature Distributions in Hypersonic Sphere Wakes
Authors: Dionne J. G. G. , Tardif L.
Published: April 2011

The radial and axial dependence of the mass density distributions in both the laminar and turbulent wakes of 1.0 and 2.7 in. diameter spheres flown at Mach 13.5 in nitrogen atmospheres have been determined using the electron beam fluorescence probe technique. The distribution of temperature in the wake has also been inferred by invoking the assumption that the wake is isobaric. Both the distribution of mass and the distribution of temperature in the wake may be characterized by the behavior of 2 parameters: the amplitude of the mass density or temperature on the center line of the wake and the corresponding profile width. Experimental data are presented for these parameters.
Scattering Properties of Certain Conducting Cylindrical Geometries
Authors: Shafai L. , Bhartia P.
Published: April 2011

Electromagnetic fields in the presence of a particular conducting cylindrical geometry are investigated. The cross section of the geometry is an area enclosed by two circular arcs of arbitrary radius which varies from a circle to a single circular arc. An integral equation for the induced current on the surface of the geometry is obtained and the total and scattered field patterns are computed.
Excitation of the Resonance Lines of Ar by Electrons
Authors: McConkey J. W. , Donaldson F. G.
Published: April 2011

'Polarization-free' measurements are presented of the electron impact excitation of the 1048 Å and 1067 Å resonance lines of argon in the energy range 10–2000 eV. Cross sections are made absolute by normalizing to the optical oscillator strength of the 1048 Å line. Cascade is shown to play a major role in the excitation of the 4s levels. Comparison is made with other experimental results and with theory where available.
Theory of Phonon Induced Anisotropy in h.c.p. Metals: Zn
Authors: Truant P. T. , Carbotte J. P.
Published: April 2011

We present a formulation of the electron–phonon interaction which applies to the case of two atoms per unit cell. Realistic Born–von Kármán phonons are used and the electron–ion interaction is treated in pseudopotential theory. Detailed numerical results are presented for the specific case of Zn. The electron–phonon function α2(ω)F(ω) which enters the electron self-energy and the superconducting properties is calculated. Associated directional functions which allow a discussion of the anisotropy in the electron–phonon interaction are also given. They are employed in a discussion of the anisotropy that enters the electron–phonon mass renormalization as well as scattering times.
Fluctuations des Mouvements de Vibration et de Rotation de CO et HCl Dissous dans CCl4. Analyse Théorique par Spectroscopies Infrarouge et Raman
Authors: Guissani Y. , Leicknam J. C.
Published: April 2011

Theories of infrared and Raman spectra of liquids are discussed, and the band shapes of HCl and CO dissolved in CCl4 are analyzed. Both monomolecular vibrational and rotational movements are detected by this study.
Coherence Transfer Between the 32P1/2 and 32P3/2 States in Sodium, Induced in Collisions with Noble Gas Atoms
Authors: Niewitecka B. , Krause L.
Published: April 2011

Coherence transfer accompanying 32P1/2 → 32P3/2 excitation transfer in sodium, induced in collisions with noble gas atoms, has been investigated using methods of sensitized fluorescence. Oriented 32P1/2 sodium atoms were produced by irradiating a mixture of sodium vapor and a noble gas with D1σ+ resonance radiation, and their subsequent collisions with the buffer gas atoms resulted in the simultaneous transfer of coherence and excitation from the 2P1/2 state to the 2P3/2 state. Measurements of the ratio of circular polarizations of the D2 sensitized fluorescence and D1 resonance fluorescence resulted in the following cross sections for coherence transfer. Na–He : 7.1 ± 0.7 Å2; Na–Ne : 6.2 ± 0.6 Å2; Na–Ar : 12.0 ± 1.2 Å2; Na–Kr : 6.8 ± 0.7 Å2; Na–Xe : 6.9 ± 0.7 Å2.
On the Fundamental Infrared Absorption of H2 and D2 in Solid Rare Gases
Authors: Taylor D. W. , Remigis J. De
Published: April 2011

A theory of the infrared absorption due to the phonon sidebands on the vibrational/rotational transitions of H2 molecules that are substitutional impurities in crystals is formulated in terms of displacement/displacement Green's functions. A sum rule for this absorption is derived and applied in detail to the systems H2/Ar, H2/Kr, and D2/Ar for comparison with the experimental results.
Delves Variational Principle Applied to Li+ Using a Numerical Excited Hartree–Fock Basis
Authors: Sokoloff J.
Published: April 2011

Calculations of improved expectations given by the Delves variational principle for the 1S state of He have been extended to the 1S state of Li+. Unlike He, Li+ supports a bound excited Hartree–Fock spectrum. Results for [Formula: see text] and [Formula: see text] indicate substantial improvement, but the improvement is not as dramatic as that given for these operators in He.
Radial–Axial Transient Heat Conduction in a Region Bounded Internally by a Circular Cylinder of Finite Length and Appreciable Heat Capacity
Authors: Kierkus W. T. , Mani N. , Venart J. E. S.
Published: April 2011

The problem of two-dimensional transient heat conduction from a circular cylinder of finite length and appreciable heat capacity has been solved using a Laplace transformation with respect to time and a finite Fourier sine transformation with respect to the axial variable. A case of constant surface heat flux with the ends of the cylinder maintained at zero temperature is considered. The solution, valid for all values of time, is compared with that of Jaeger for the infinitely long cylinder. The results are of use in the evaluation of heat losses for the transient hot-wire method of determining the thermal conductivity of fluids.
The Spark Spectra of Na IV and Na VI
Authors: Goto T. , Gautam M. S. , Joshi Y. N.
Published: April 2011

The spark spectra of sodium have been obtained in the region of 80 to 2400 Å using a θ-pinch and a triggered vacuum spark as sources. Analysis of the data has led us to establish nine new levels in Na IV and to classify 40 new lines in this spectrum. An additional level has been found in Na VI resulting in the classification of 4 new lines.
On the Scale Dimension of Conformally Covariant Spinor Fields
Authors: Drew Mark S.
Published: April 2011

The spinor equation of Barut and Haugen is shown to admit no solutions having a definite scale dimension in Minkowski space.
Unified Space-Time Trigonometry and its Applications to Relativistic Kinematics
Authors: Jaccarini Antoine
Published: April 2011

This paper presents a geometrical approach to relativistic kinematics. Owing to a unified space-time trigonometry, the spherical trigonometry formalism may be used to describe and study the kinematics of any collision process. Lorentz transformations may thus be treated as purely geometrical problems.A different way to define a unified trigonometry is also proposed, which is based on the spinor representation of the Lorentz group. This leads to a different and more general formalism than the former one.
Multiple Scattering by Two Centers of Force
Authors: Gauthier L. , Razavy M.
Published: April 2011

A solvable model for scattering by two centers of force is studied. The force at each center is assumed to be a separable force acting on the S wave only. A force law of this kind enables one to find the scattering amplitude for overlapping as well as nonoverlapping potentials analytically. The resulting scattering amplitudes can be used to compare the range of validity of the Born and other high energy approximations and also to test the accuracy of the result obtained by retaining the leading terms in the multiple scattering series. By examining the relation between the exact scattering amplitude for the two centers and the scattering amplitude of one center, it is shown that in the case of nonoverlapping potentials, the former amplitude can be expressed completely in terms of the latter. Hence no additional information about the nature of force results from the determination of the two-center scattering amplitude. However, for overlapping potentials, one can discriminate among equivalent potentials by finding the scattering amplitude for the two-center-of-force problem. Finally to justify the use of a potential which acts only in one partial wave (l = 0), the following observation has been made. If one calculates the scattering length for two nonoverlapping hard sphere interactions, using S-wave scattering by each center, and then repeats the calculation for the same interactions but considers S and P waves and their interference, the difference between the two results will be quite small.
Light Diffraction Studies of CdS Phonon Masers
Authors: Vrba J. , Haering R. R.
Published: April 2011

Light diffraction experiments on c- and b-axis CdS phonon masers are presented and compared with the theoretical analysis presented in the previous paper. It is shown that in general the active acoustic waves do not propagate along the normal to the plane parallel sides of the crystal. The agreement with theory is good. Strain amplitudes as large as 10−4 have been observed.
Pressure Line Shape: Semiclassical and Quantum-Mechanical Calculations
Authors: Cattani M.
Published: April 2011

In this paper we study the limitations of the classical straight path approximation. With this purpose, we calculate the line shape using both the straight path and the quantum formalisms and compare the results. A simple ideal potential is considered.
Spatial Distribution of Charge Carrier Density in a Low Temperature Gas Discharge Plasma
Authors: Joshi S. B. , Chiplonkar V. T.
Published: April 2011

The spatial distribution of the charge carrier density in aglow discharge plasma of air and argon has been obtained by a double probe measurement and is shown to conform with the theoretical expectations, with appropriate modifications.
Laser-Excited Emission from Glyoxal and Its Deuterated Derivatives
Authors: Dong Ronald Y. , Ramsay D. A.
Published: April 2011

Emission spectra of glyoxal, glyoxal-d1, and glyoxal-d2 have been excited using the various lines of an argon ion laser. The bands have been assigned to 3 band systems, viz. the 1Au–1Ag and 3Au–1Ag (π*–n) systems of the trans molecule and the 1B1–1A1 (π*–n) system of the cis molecule. The vibrational constants are in good agreement with earlier values. Some new vibrational constants have been determined.
Measurement of L Subshell Yields of La by Means of Coincidence and Critical Absorption
Authors: Douglas D. G.
Published: April 2011

The L subshell yields ω2, ω3, and f23 have been measured for Z = 57 by observation of the X rays of 139Ce employing a method combining coincidence and critical absorption. The results for ω2(0.112 ± 0.009) and ω3(0.092 ± 0.008) are in fairly satisfactory agreement with theory but f23(0.21 ± 0.02), as has been shown to be the case at other Z values, exceeds theoretical predictions.
Quenching of Mercury-Sensitized Fluorescence in Sodium, Induced in Collisions with N2 Molecules
Authors: Czajkowski M. , Krause L. , Skardis G. M.
Published: April 2011

The behavior of the sensitized fluorescent spectrum of sodium, produced by irradiating Hg–Na–N2 mixtures with Hg 2537 Å resonance radiation, was studied in relation to N2 pressure. In this ternary vapor-gas system, the sodium atoms become excited by collisional transfer from Hg 63P1 atoms and also from Hg 63P0 atoms which are formed in Hg(63P1) + N2 collisions. The spontaneous decay of the collisionally populated S, P, and D sodium states gives rise to the fluorescent spectrum and their radiationless decay (quenching) caused by collisions with N2 molecules, manifests itself in a decrease of the fluorescent intensities as N2 pressure is increased. An analysis of the variation of the fluorescent intensities with N2 pressure, yielded 15 quenching cross sections for various S, P, and D sodium states, which appear to exhibit resonance properties with respect to upward vibrational transitions in N2.
Raman Spectrum of TlCl0.6Br0.4 near Resonance
Authors: Krishnamurthy N. , Torrie B. H.
Published: April 2011

Raman scattering from single crystals of TlCl0.6Br0.4 has been observed both as a function of temperature and excitation wavelength. The spectra exhibit strong one-phonon Raman scattering at 17 and 37 cm−1 and a weak two-phonon band centered at 296 cm−1, close to twice the LO frequency (q = 0) of the mixed crystal. From the temperature dependence and the calculated one- and two-phonon densities of states, it is shown that the 37 cm−1 line and the tail following it are an admixture of first- and second-order Raman scattering. The enhancement of the intensity of the 296 cm−1 band when the exciting wavelength is decreased from 5145 Å to 4545 Å is attributed to the resonant-scattering mechanism proposed by Fontana and Mulazzi.
Improved Spectroscopic Data Synthesis for I2(B3ΠOu+) and Predictions of J Dependence for B(3ΠOu+)–X(1Σg+) Transition Intensities
Authors: Brown J. David , Burns George , Roy Robert J. Le
Published: April 2011

Some new techniques are introduced in a reanalysis of the spectroscopic data for I2(B3ΠOu+)to obtain a more complete and internally consistent set of molecular constants, and an RKR potential curve. In particular, attention is focussed on the determination of reliable high-order rotational constants (Dν, Hν, etc.) for highly excited vibrational levels. The ensuing intermolecular potential for this state is then used together with a known ground-state curve in a study of the J dependence of Franck-Condon factors for discrete B(3ΠOu+)–X(1Σg+) transitions over a wide range of ν and J. It is concluded that at the temperatures 1000–2000 °K routinely achieved in shock-tube experiments, the intensity of most vibrational bands will vary drastically as J ranges across the half-width of the thermal rotational population distribution.
Knock-On Mechanism for (n,α) Reactions Induced by Fast Neutrons on the Deformed Odd–Even Nuclei
Authors: Głowacka L. , Jaskóła M. , Kozłowski M. , Osakiewicz W. , Turkiewicz J. , Zemło L.
Published: April 2011

A method for the calculation of the energy spectra of α particles from (n,α) reactions on deformed odd–even nuclei is developed. The resulting energy spectra for 14 MeV (n,α) reactions in 153Eu, 159Tb, and 169Tm are compared with experimental data. Agreement reached suggests the dominance of the knock-on mechanism in the investigated reactions.
Scattering by Two Impenetrable Spheres
Authors: Razavy M.
Published: April 2011

The problem of multiple scattering by two rigid spheres is studied in the context of an effective range theory. At low energies, by expanding the total wave function in powers of the momentum of the incident particle, it is observed that the coefficients of different terms of the expansion are solutions of either Laplace or Poisson equations. These equations are separable in bispherical coordinates. Using the method of separation of variables, one can determine the scattering amplitude and its first and second derivatives with respect to momentum, at zero energy. In particular, a simple expression is obtained for the scattering length of two hard spheres. With the help of the Green's function in bispherical coordinates, it is shown that for any wavenumber, the scattered wave satisfies an inhomogeneous integral equation in two variables. Hence, the exact wave function and the scattering amplitude can be found numerically for all energies.
Reststrahlen of Alkali Halides in the Far-Infrared Region
Authors: Leung A. F.
Published: April 2011

The assumption in deriving the Lyddane–Sachs–Teller relation and the simple harmonic oscillator model do not hold well in the understanding of the optical properties of alkali halides in the far-infrared region.
Collision-Induced Light Scattering in Liquids and the Binary Collision Model
Authors: Ho J. H. K. , Tabisz G. C.
Published: April 2011

The collision-induced Rayleigh wing in the depolarized light scattering spectrum of five molecular liquids has been studied in order to try to assess the validity of the isolated binary collision model. The intensity profiles have been analyzed in terms of the expressions derived by Bucaro and Litovitz, [Formula: see text], and by Shin, [Formula: see text]. It is concluded that before a positive distinction can be made between models or before reliable information on molecular dynamics may be extracted from the spectrum, a good theoretical estimate of the form of the induced polarizability Δα for close collisions is required.
Collisional Excitation of Ground State Hydrogenic Ions
Authors: Tully John A.
Published: April 2011

The nonrelativistic Coulomb–Born approximation has been used to compute scaled collision strengths for electron impact excitation of the 1s → ns, np, nd transitions in hydrogenic ions. Results are given for n = 2, 3, 4, 5, 6, [Formula: see text] as a function of the incident electron energy in threshold units. Simple formulae for interpolating the tabulated results are also given.
Hartree–Fock Ionization Potentials of Atoms
Authors: Fraga S. , Saxena K. M. S. , Karwowski J.
Published: April 2011

Values of the first four ionization potentials have been calculated from Hartree–Fock energies, with and/or without the relativistic corrections, for the elements lithium to nobelium. The merit of the Hartree–Fock approximation, regarding the prediction of ionization potentials, is discussed by comparison to existing experimental data.
Theoretical and Experimental Line Profiles of Autoionizing States as Reflected in their Electroionization Curve
Authors: Bolduc E. , Marmet P.
Published: April 2011

An expression is deduced to predict the profiles encountered when autoionizing neutral states are detected. The validity of the new equation is shown by comparison with a structure detected in the electroionization curve of neon and attributed to the autoionizing 2s22p43s2(3P) state of neon. The new expression furthermore explains why the structure 2s2p63s(1S) of neon appeared missing in previous work.
Growth Characteristics of Turbulent Wakes
Authors: Lahaye C. , Doyon P.
Published: April 2011

Recent advances in the experimental study of hypersonic wakes at the Defence Research Establishment Valcartier have led to spatially resolved measurements of the behavior of the important physical variables which characterize the wake. Previous measurements pertained mainly to the wake growth, and they were achieved by an integrated-type technique using a schlieren system under test conditions different from those utilized at this establishment. To assist in relating the new measurements with the earlier ones, and to provide a basis for comparing growth results obtained from the spatially resolved measurements, schlieren films of model wakes taken during this program have been utilized to obtain wake growth data at the same velocities and pressures as those of the spatially resolved measurements. Both cone and sphere wakes have been investigated. Results show that the effect of P∞D (pressure times body diameter) on wake growth is negligible, while the Mach number has a strong effect. Turbulent wake growth can be described by the expression: [Formula: see text], where both the wake width Dw and the axial distance X have been normalized by the drag diameter [Formula: see text]. The factor C is a function of the Mach number M∞: C = 0.56 + 0.032 M∞.
Small Angle Elastic Scattering of 4.3 MeV Neutrons From U, Bi, and Pb
Authors: Martin P. W. , McFadden R. , White B. L.
Published: April 2011

The differential cross sections for 4.3 MeV neutrons elastically scattered from natural samples of U, Bi, and Pb have been measured at laboratory angles of 5, 10, and 15°. In the case of uranium, the data are consistent with calculations based on the nuclear optical model and known electromagnetic interactions. Less satisfactory agreement to the data is obtained in the cross section measurements for lead and bismuth.
Negative and Neutral Autoionizing States Detected in the Electroionization Curve in CO
Authors: Carbonneau R. , Marmet P.
Published: April 2011

Negative ion resonances and neutral Rydberg states having the A2Π and B2Σ+ states of CO+ as limits are reported for the first time in the electroionization curve of CO. Moreover, new doubly excited states of CO are observed around 21 eV. The electroionization is compared with photoionization, photoabsorption, and electron transmission when data are available.
Electrical Resistivity of Noble Metals
Authors: Pal Satya
Published: April 2011

The temperature variation of the electrical resistivity of copper, silver, and gold has been studied within the free electron approximation on the basis of the lattice dynamical models of Chéveau, and Bhatia and Horton. The first-order variational solution of the Boltzmann transport equation as developed by Ziman has been incorporated in the study for the calculation of the transport coefficients of noble metals. The force constants appearing in the secular equation for the lattice vibrations have been estimated with the help of the experimental values of the elastic constants of the noble metals. The phonon spectrum has been calculated by the modified Houston spherical six-term procedure as elaborated by Betts et al. The Normal and the Umklapp contributions to the electrical resistivity have been considered separately in the present study. A comparison of the theoretical results with the experimental data shows that the calculations are able to explain satisfactorily the temperature dependence of the electrical resistivity of the noble metals. However, as compared to the Bhatia–Horton model, the theoretical resistivity values of the noble metals as furnished by the Chéveau model give a better overall fit with the experimental data.
Oscillating Progressive Shear Waves in Nonhomogeneous Viscoelastic Solids
Authors: Moodie T. Bryant
Published: April 2011

The equations of motion for cylindrical and spherical shear waves in nonhomogeneous, isotropic, "standard", viscoelastic media with continuous radial variations are derived. Oscillatory shearing tractions are applied to the boundaries of cylindrical and spherical openings in unlimited viscoelastic media. The propagation of small-amplitude waves is studied, and formal asymptotic expansions of the solutions are obtained. In both cases (cylindrical and spherical), the leading term of the formal asymptotic expansion represents a modulated, oscillating, progressive wave propagating with variable velocity. The modulation depends on the moduli of rigidity and viscosity, whereas the velocity depends on the moduli of rigidity only. Application of our results to the propagation of shear waves in both finite and infinite viscoelastic plates is discussed.
Pressure Broadening of the Microwave Absorption Lines of Oxygen
Authors: Yamamoto Y. , Cattani M.
Published: April 2011

We calculate the line widths for the self-broadening of the microwave spectrum of oxygen taking into account simultaneously quadrupole–quadrupole and dispersion interactions. Our theoretical results are compared with the more recent experimental results. A good agreement is obtained between them if the oxygen quadrupole moment is taken as Q = 1.21 ± 0.05 D Å.
Theory of the Line Shape in Quadrupole-Induced Infrared Spectra
Authors: Kranendonk J. Van , Gass D. M.
Published: April 2011

The variation of the line width of the rotational components in the pressure-induced infrared spectra of H2–inert-gas mixtures is calculated. At low densities, the contribution of the R-modulation effect to the line shape is calculated assuming quadrupolar induction and neglecting intercollisional interference effects. The observed line narrowing at high densities is interpreted in terms of a model for the stochastic modification of the binary dynamics resulting from multiple collisions, and described in terms of the diffusion coefficient of the gas mixture. The width at high densities is shown to be proportional to the diffusion coefficient, in agreement with a previous simplified analysis.
Electric Dipole Moment of Propynal in the ã3A′ State
Authors: Dong Ronald Y. , Ramsay D. A.
Published: April 2011

The Stark effect on the rotational lines of the 0–0 band of the [Formula: see text] system of propynal has been studied with field strengths up to 20 kV/cm. Measurements of the Stark shifts and splittings for the qQQ2(7,7), qQQ2(8,8), and qQQ2(9,9) lines in parallel polarization lead to a value of µa′ = 0.5 ± 0.1 D for the dipole moment of propynal in the ã3A″ excited state.
The Microwave Permeability of a Ferrite-Filled Parallel-Plate Transmission Structure
Authors: Campbell C. K.
Published: April 2011

With the aid of a phasor diagram it is shown that the scalar effective permeability μe = (μ2 − K2)/μ of a parallel-plate longitudinally magnetized microwave ferrite phase shifter may be simply obtained in terms of four circularly polarized waves relating to the permeability tensor eigenvalues μ + K and μ − K.
Decay of a 1.4 μs State in 151Sm
Authors: Cook W. B. , Waddington J. C.
Published: April 2011

A pulsed beam of alpha particles was used to excite the 261 keV level in 151Sm through the 148Nd(α,nγ) reaction. This level was found to decay with a 1.4 ± 0.1 μs half-life to the 65.83, 91.53, 147.9, and 175.38 keV states. As has been found for heavier odd-neutron nuclei in this region, this isomeric state is probably the 11/2−[505] Nilsson orbital.
Geometric Approaches to Relativistic Kinematics
Authors: Yaccarini Antoine
Published: April 2011

A comparison is made, between three methods for visualizing the Minkowski space, in view of their application to relativistic kinematics.The velocity manifold method, in which a vector is represented by a point on the upper sheet of the unit-radius hyperboloid, presents two advantages: there is no distortion of angles, and the method is independent of the choice of any particular frame or observer. It is, however, limited to the representation of positive timelike vectors.The Cayley map method allows the representation of spacelike as well as timelike vectors, but it has two drawbacks: it distorts the angles, and it depends on the choice of a reference system.In the third method, the use of a unified space–time formalism permits one to visualize any kind of vector. This method generalizes the velocity manifold method, and presents the same two advantages: it provides us with a conformal representation, which is independent of any particular observer.We also present a rather concise comparison between two covariant methods of calculation, considered from the point of view of relativistic kinematics. One method is the familiar tensor calculus; the other is the spinor calculus, based on the representation of four-vectors by matrices.
Band Mixing in the 2s–1d Shell: Application to 23Na
Authors: Haas B. , Taras P.
Published: April 2011

Formulas treating correctly hole excitations and the j2 term in the context of the strong coupling collective model are presented. It is found that such a treatment gives rise to appreciable differences from the usual band mixing calculations of nuclei in the 2s–1d shell. As an illustration, the nucleus 23Na will be discussed. This nucleus, with a large ground state quadrupole moment, seems to be an ideal candidate for the application of the unified model. Although the model reproduces the energy level scheme quite well, it fails, rather badly, to explain the observed electromagnetic transition properties of a number of levels.
Critical Attenuation of Ultrasound in Argon
Authors: Ward P. W. , Cowan J. A. , Pathria R. K.
Published: April 2011

Ultrasonic attenuation measurements have been made in argon at temperatures above Tc in the frequency range 5–15 MHz and over a range of densities around the critical density ρc. The critical attenuation per wavelength, measured along the critical isochore, conforms to the theoretical prediction that it depends only on the reduced frequency ω* = ω/ωD, where the characteristic frequency ωD = (2K/ρCp)ξ−2. Comparison with theory leads to the empirical result: ξ = 1.8ε−2/3 Å, where ε = (T − Tc)/Tc. It is pointed out that the corresponding data pertaining to the liquid phase, along the coexisting curve, can also be expressed in terms of the single reduced variable ω*.
An Interpolation Formula for the Energy Radiated by a Point Charge Passing Through a Hole in a Plane
Authors: Maresca Neal J. , Liboff Richard L.
Published: April 2011

The radiative energy loss [Formula: see text] accompanying the transition of a uniformly moving nonrelativistic point charge e through a hole of radius a in an infinite, ideally conducting plane is obtained. The technique of solution involves a quasistatic approximation to the dynamic problem in the regime [Formula: see text]. In this limit, the presence of the hole is found to induce an array of slowly accelerating linear multipoles whose associated radiation leads to a finite energy loss proportional to β3. An interpolation formula [Formula: see text] for the energy loss valid for arbitrary β is constructed from this result and the known ultrarelativistic expression. Application of this formula in conjunction with the relativistic Maxwellian allows computation of a temperature dependent, radiation loss expression appropriate to the passage of a relativistic pulse through an iris-type aperture. A formula incorporating finite beam length coherence effects for the radiation loss in low energy particle accelerators is also developed.
Theory of Resonance Broadening Including the Duration of Collision Effects
Authors: Zaidi H. R.
Published: April 2011

Theoretical expressions are derived for the complete line shape in resonance broadening using two independent methods, viz. (a) propagator techniques, (b) kinetic theory techniques. These expressions are valid for any duration of collision in the binary collision regime, and reduce to the impact (static) limit results when the average duration of collision is small (large). The expressions involve the Fourier transform of the two body collision operator and, therefore, these are quite suitable for actual numerical calculations.
Coherent X-ray Scattering Factors for Various Configurations of Lanthanides and Their Positive Ions
Authors: Benesch Robert , Saxena K. M. S.
Published: April 2011

Coherent X-ray scattering factors have been computed from numerical Hartree–Fock wave functions for the neutral lanthanides and for their single-, double-, and triple-positive ions having the most commonly occurring 6sm4fn ground state configurations. For small scattering angles, the scattering factors for the ions vary among the various configurations. At large scattering angles all configurations for a given ion yield similar values for the scattering factor.
Branching Ratios and Lifetimes of 25Mg Levels between 5.2 and 6.1 MeV
Authors: Ollerhead R. W. , Kean D. C. , Leong S. G. T. , Doekes C. , Meadley T. M. R.
Published: April 2011

All levels between 5.2 and 6.1 MeV in 25Mg have been studied using the reaction 25Mg(p,p′γ). Inelastically scattered protons were detected in an annular surface barrier detector located at 180°; coincidence gamma-ray spectra were obtained at Ge(Li) detector angles of 90, 45, and 135°. Level energies were determined from unshifted gamma-ray energies recorded in the 90° spectra. Lifetimes were obtained from the attenuated Doppler shift of gamma-ray energies recorded in spectra taken at forward and backward angles. Branching ratios were deduced from the combined data of all three angles. The identification of levels as members of rotational bands is discussed, and transition strengths deduced from the present measurements are compared with predictions of the simple rotational model. In particular, evidence is presented for the identification of a level at 5535 keV as the 11/2 member of the ground state band, levels at 5522 and 5794 keV as the 5/2 and 11/2 members of the Kπ = 1/2− band, and a level at 6040 keV as the 11/2 member of a Kπ = 9/2+ band.
On the Displaced Lattice Charge and Residual Resistivity
Authors: Popović Z. , Carbotte J. P.
Published: April 2011

We have used the method of lattice statics to perform microscopic calculations of the displaced lattice charge far away from an impurity in an alkali metal. The displaced charge is then used to determine with the aid of the continuum approximation the change in solid structure factor and from it to estimate the correction to the residual resistivity due to strain. Our approximate results for this correction are compared with exact lattice static results and it is found that the continuum approximation very often seriously underestimates the effect of strain.
Excitation de H2 et D2 par impact électronique au voisinage du seuil d'ionisation
Authors: Roy D. , Carette J.-D.
Published: April 2011

This paper reports results about energy losses of slow electrons (~100 eV) which are scattered in the forward direction by molecular hydrogen and deuterium. The region near the ionization threshold has been investigated with great care in order to determine the contribution of electronic states B′, D, B″, D′, and D″ to the excitation of these molecules through this channel, and also to determine if this scattering channel allows one to obtain evidence of direct ionization and autoionization.
Optical Absorption Spectra of the A Band in KBr:Pb2+ Crystals
Authors: Tsuboi Taiju , Chaney Robert E. , Jacobs P. W. M.
Published: April 2011

The shape of the A band in KBr:Pb2+ has been studied at various temperatures between 13 and 296 K. The band is almost symmetric at low temperatures but slightly asymmetric at high temperatures. The observed line shape of the A band in KBr:Pb2+ is discussed in terms of the Jahn–Teller effect and is compared with that of the A band in In+ and Tl+ doped alkali halides.
Molecular Parameters for the a3Πu and b3Σg− States in C2
Authors: Veseth L.
Published: April 2011

Molecular parameters for the a3Πu and b3Σg− states in C2 (Ballik–Ramsay system) are determined by a nonlinear least squares fit directly to the observed wavelengths. No satellite lines are observed in the electronic spectra of C2, and the influence of nuclear statistics yields further restrictions with regard to observable lines. The present approach, however, yields accurate values of the various triplet splitting and Λ-doubling parameters in spite of this lack of experimental information. Finally a refined value of the triplet–singlet energy separation is obtained.
Theoretical Oscillator Strengths for nS–mP Transitions in Mg
Authors: Fischer Charlotte Froese
Published: April 2011

Theoretical oscillator strengths for the 3s ns1,3S–3s mp1,3P transitions of Mg are reported for n,m = 3,4,…,7.The results are based on an MCHF approximation to the total wave function which includes the correlation of the outer two electrons.
Acoustical Dispersion in Periodic Microwave Structures
Authors: Aboul-Atta O. A. , Tomchuk E.
Published: April 2011

The theory, the design, and the numerical results relevant to the acoustical frequency dispersion band of periodic microwave structures are discussed. Experimental Brillouin diagrams for the acoustical band of different structures exhibit a neat fitting to a special curve. This curve coincides with the qualitative analysis of resonators chain coupled (distant coupling included) together both capacitively and inductively. Discrete points on the curve are obtained analytically using the variational theory. Those points which correspond to the eigenvalues of only one period of the structure are analyzed and explained in terms of boundary conditions. Numerical methods for calculating these eigenvalues to a high degree of accuracy are either already available or can easily be programed. These programs are easily modified so that various other design parameters may be evaluated simultaneously. The basic equations are derived and the appropriate technique developed for a model of distant coupling up to the second neighbor. Comments on the numerical procedure, on the accuracy, and on the practicality of the different operational modes are given.
Remarks on the Spectrum of Gaseous SeO
Authors: Barrow R. F. , Lemanczyk R. Z.
Published: April 2011

The emission bands observed by Azam and Reddy and ascribed by them to two systems, b1Σ+, a1Δ–X3Σ−, of SeO are shown to arise from a single system, b1Σ+–X3Σ−. Head-origin separations are employed to derive rough values of Bν′ and these in turn are used to estimate band-origins and thence vibrational constants. The values of the constants derived for b1Σ+ of 80SeO are as follows: Tc = 9724.1 cm−1 (with respect to the minimum in the Ω = 0+, F1 component of X3Σ−, Gν = 836.58(ν + 1/2) – 5.11(ν + 1/2)2, and Bν = 0.457 – 0.0034(ν + 1/2). The separation (Ω = 1)c – (Ω = 0+)c in the ground state is found to be 165.8 cm−1.
On the Calculation of the Fundamental Mode of the One Velocity Neutron Transport Operator
Authors: Rangaswamy Lakshmi , Ahmed Feroz
Published: April 2011

We report here the P1 and P3 solutions (eigenvalues and eigenfunctions) for the case of one velocity pulsed slabs.