bluuebunny/crossref_metadata_2025 huggingface dataset:
A Kπ = 0− Octupole Band in 150Sm
Authors: Thompson J. V. , Johns M. W. , Waddington J. C.
Published: April 2011

A study of the 148Nd(α, 2n)150Sm reaction has revealed the high spin states of a Kπ = 0− octupole band, the members of which become the yrast levels above spin 12. Gamma ray angular distributions, gamma–gamma coincidence, and conversion electron studies have established the levels of the octupole band at 1764.6(7−), 2232.1(9−), 2744.0(11−), and tentatively at 3293.0(13−) keV.
The Specific Mass Shift of the Resonance State and Resonance Line in Li I
Authors: Migdałek J. , Leś Z. , Banasińska E.
Published: April 2011

The specific isotope effect caused by the difference between the nuclear masses of Li 6 and Li 7 has been calculated for the Li I 22P term and for the 6708 Å (2 2S – 2 2P) resonance line. The wave function used in the calculation has been obtained by a semiempirical method based on the linear deformation of the atomic core.
Development of Closure Relations in Kinetic Theory
Authors: Baganoff Donald , Elliott James P.
Published: April 2011

A systematic method of obtaining closure relations for Maxwell's moment equations is developed, and shown, by application to the problem of an infinitely strong shock wave, to lead to results at the fourth order truncation level which agree with Mott–Smith and Monte Carlo predictions.
Diffraction of Electromagnetic Waves by a Semi-Infinite Screen in a Layered Medium
Authors: Heitman Wiebe G. , Berg P. M. van den
Published: April 2011

The diffraction of a plane electromagnetic wave by a semi-infinite screen in one of the plane interfaces of a layered medium is investigated theoretically. The screen of vanishing thickness is assumed to be electrically perfectly conducting. Two separate two dimensional scalar problems are dealt with, viz. the case of E polarization and H polarization. The resulting unknown field functions are determined with the aid of the Wiener–Hopf technique. Subsequently, the electromagnetic power flow density is calculated at different locations and as a function of the electromagnetic contrast of the different media.
Theory of the Spin Susceptibility of an Inhomogeneous Electron Gas via the Density Functional Formalism
Authors: Vosko S. H. , Perdew J. P.
Published: April 2011

The density functional theory of Hohenberg, Kohn, and Sham has been used to derive an exact variational expression for the spin susceptibility (χ) of an inhomogeneous electron gas. This variational expression allows one to simultaneously treat band and exchange correlation effects among the conduction electrons and, furthermore, includes the influence of core electrons on the latter. The use of a simple trial function and a local approximation for the exchange correlation functional in the variational expression results in a simple formula for χ (lower bound). The above approach is developed in parallel and compared with the self consistent single particle equations for a magnetized paramagnetic system including exchange correlation. These equations are used to obtain explicit expressions for the paramagnetic response functionals for noninteracting and interacting systems.
Alpha Particle Emission from 16O and 20Ne in the Giant Dipole Resonance Region
Authors: Skopik D. M. , Shin Y. M. , Murphy II J. J.
Published: April 2011

The electrodisintegration cross sections, 16O(e,α0)12C,e′ and 20Ne(e,α0)16O,e′, have been measured and, by using virtual photon analysis, a comparison with photodisintegration experiments has been made. Satisfactory agreement with earlier 12C(α,γ0)16O experiments was found and the 20Ne(γ,α0)16O reaction reveals several pronounced resonances.
Current–Voltage Characteristics of Single Crystal Cu2O Diodes
Authors: Chee K. T. , Weichman F. L.
Published: April 2011

The I–V characteristics of Cu2O diodes, made from high resistivity single crystal Cu2O bonded to copper, are reported. The forward I–V characteristics below 60 °C are found to exhibit [Formula: see text], [Formula: see text], and [Formula: see text] regions (appearing in that order as the voltage increases), while at higher temperatures the [Formula: see text] region disappears. The assumption of a space–charge limited region permits the explanation of the data.The temperature dependence of the I–V characteristics in the [Formula: see text] region is studied in greater detail and is explained by the existence of shallow traps with trap energy 0.26 eV above the valence band edge.
The Photoconductive Response in a-ZnTe
Authors: Webb J. B. , Brodie D. E.
Published: April 2011

The photoconductive response in amorphous zinc telluride (a-ZnTe) has been studied as a function of both light intensity and temperature. A peak in the log photoconductivity vs. reciprocal temperature plot is observed which moves to higher temperatures with increasing incident light intensity. At temperatures greater than Tmax (the temperature at which the photoconductivity is a maximum), the recombination process is monomolecular. At temperatures below Tmax, the recombination is bimolecular. The results are consistent with the Mott and Davis model (DM model) for amorphous materials. For a given incident light intensity, the characteristics of the photoconductive response change as a function of temperature. The effects can be explained on the basis of the trapping of carriers in localized states at the band edge to form charged scattering centers. This is consistent with measurements of thermally stimulated currents in this material. The effect of these trapped carriers is to increase the scattering of carriers in the extended states. The results obtained from the photoconductivity in a-ZnTe and previous results from measurements of the d.c. conductivity and Seebeck coefficient (Webb and Brodie) have allowed the construction of a band diagram for a-ZnTe based on the DM model and the complete band diagram is given.
Micromagnetics and Magnetostatics of an Iron Single Crystal Whisker
Authors: Bloomberg D. S. , Arrott A. S.
Published: April 2011

The magnetization process of an oriented iron single crystal is investigated. A solution of the micromagnetic equations for a multidomain configuration in an applied field demonstrates the dominance of magnetostatics in determining the susceptibility. The magnetic charge is found to be almost entirely on the surface, justifying the model of a fictitious medium of constant intrinsic susceptibility. This model is then used to explain the observed small coil susceptibility. Analytic expressions for the susceptibility and for an upper limit on the volume charge density (div M) are also developed. The major results of the magnetostatics calculation can be summarized by a useful local approximation for the demagnetizing field.
A Fast Fourier Transform Study of the Proton and Deuteron Line Shapes of Some Selected Nematics
Authors: Visintainer J. J. , Bock E. , Dong Ronald Y. , Tomchuk E.
Published: April 2011

Proton and deuteron Fourier transform magnetic resonance spectra are reported for a variety of nematic liquid crystals. We discuss the widening of the dipolar splittings of phenylene protons due to terminal proton groups, which results in the incorrect measurements of the degree of order. 'Fine structure' in the proton spectra is related to the rotating methyl groups.
ESR Linewidths of Vanadyl β-Diketonate Complexes in Liquid Solutions
Authors: Eagles T. E. , McClung R. E. D.
Published: April 2011

The electron spin resonance (ESR) spectra of a series of vanadyl β-diketonate complexes in dilute solutions in several inert solvents have been investigated. The widths of the lines in these spectra have been interpreted in terms of the Kivelson linewidth theory. Significant discrepancies between the experimental linewidths and those predicted by the theory were found at low temperatures and high solvent viscosities. It is concluded that the Stokes–Einstein relationship, which relates the reorientational correlation time to the solvent viscosity, is not valid in the low temperature region and that the simple description of spin relaxation by the spin–rotational interaction given by Atkins and Kivelson is inadequate.
Periodicity of the Oscillatory J Dependence of Diatomic Molecule Franck–Condon Factors
Authors: Roy Robert J. Le , Vrscay Edward R.
Published: April 2011

Numerical calculations have shown that vibration–rotation interaction often contributes significantly to the J dependence of transition intensities of diatomic molecules. This occurs because centrifugal displacements of the vibrational wave functions cause the Franck–Condon amplitudes (radial overlap integrals) to behave as oscillating functions of J(J + 1). The present paper discusses the origin of this behavior and derives and tests a simple formula for predicting the periodicity of such oscillations. This procedure requires only a knowledge of the rotational constants and vibrational spacings of the initial and final states. It utilizes the result that the average centrifugal displacement rate of a diatomic molecule's radial wave function is approximately [Formula: see text], where Bν and Dν are the usual diatomic rotational constants.
A Doublet–Quartet Perturbation in CN
Authors: Coxon J. A. , Ramsay D. A. , Setser D. W.
Published: April 2011

The perturbation of the N = 20, ν = 11 levels of the B2Σ+state of CN has been examined in high resolution spectra of the 11–11 and 11–10 violet bands. There is strong evidence that the perturbation is produced by a previously unobserved 4Σ state.
Magnetoresistance of TTF-TCNQ
Authors: Tiedje T. , Carolan J. F. , Berlinsky A. J. , Weiler L.
Published: April 2011

The magnetoresistance of TTF-TCNQ has been measured for currents along the crystallographic b axis in static fields of 50 kOe for temperatures between 17 and 98 K. For [Formula: see text] the magnetoresistance Δρ/ρ = [ρ(50 kOe) − ρ(0)]/ρ(0) is less than 0.1% in magnitude. There is a peak of about −1.4% at 52.8 ± 0.2 K. Below 50 K, Δρ/ρ is small and negative and is described reasonably well by the formula Δρ/ρ = −(1/2)(μBH/kT)2. At all temperatures Δρ/ρ was found to be approximately independent of the orientation of the applied field with respect to the current. The high temperature behavior is consistent with that expected for a metal in the short scattering time limit [Formula: see text]. We attribute the peak at 52.8 K to the suppression of the metal–insulator transition by the magnetic field, and we show why such behavior would be expected for a Peierls transition. In the low temperature region the crystal acts like a small gap semiconductor for which the –T−2 dependence of Δρ/ρ is easily understood. We note that the peak in the magnetoresistance at 52.8 K strongly suggests that the electronic energy gap goes to zero at this temperature. One is then led to conclude that the decrease in the conductivity between 58 and 53 K is due to resistive fluctuations above the metal–insulator transition.
Raman Scattering in GaSe
Authors: Hoff R. M. , Irwin J. C. , Lieth R. M. A.
Published: April 2011

Raman spectra have been obtained from both the ε and γ polytypes of GaSe. The frequencies of the phonons at the zone center have been obtained for both compounds at 80 K and at 295 K. All modes have been assigned on the basis of their observed polarization dependence to an irreducible representation of the appropriate point group. A comparison of the spectra of the two polytypes has provided further confirmation of previous identifications of the various modes in ε-GaSe. Excellent agreement has been obtained between the observed and predicted dependence of the polar mode frequencies with phonon propagation direction. No evidence of conjugate modes has been observed in any of the GaSe spectra.
Intermolecular Potentials from NMR Data: II. CH4, CF4, and SiF4
Authors: Rajan S. , Lalita K. , Babu S. V.
Published: April 2011

Proton and fluorine spin–lattice relaxation times per unit density, T1/ρ, in pure gases CH4, CF4, and SiF4 are experimentally found to be proportional to T−1.5 where T is the temperature. Using either a hard sphere or a 12–6 Lennard–Jones potential for the isotropic part of the intramolecular potential, it is shown here that these data can be analyzed to obtain information on the anisotropic part of the potential in these systems. The analysis is made within the framework of the Bloom–Oppenheim theory, assuming that the correlation time of the spin–rotation interaction can be approximated by the average lifetime of a molecule in the given J state. From the strength of the attractive term in the anisotropic potential, the octopole moments of all the three molecules are obtained. These values are comparable with the values reported earlier based on other techniques for CH4 and CF4 in case of the Lennard–Jones model. The octopole moments of CH4 and CF4 obtained from the hard sphere model are smaller by 25% than those from the Lennard–Jones model. For SiF4, we obtain values of 4.14 × 10−34 e.s.u. cm3 and 5.3 × 10−34 e.s.u. cm3, as the octopole moments from the Lennard–Jones and the hard sphere models respectively and no other value exists in the literature.
La thermoréflectance des alliages Cd3−xZnxAs2
Authors: Aubin M. J. , Cloutier J. P.
Published: April 2011

Thermoreflectance measurements have been performed on Cd3−xZnxAs2 alloys mostly at room temperature. The most important of the observed transitions are E1 and E1 + Δ1 whose energies agree with the reflectivity results of Sobolev et al. and the calculations of Lin-Chung for Cd3As2(x = 0). As for Zn3As2(.x = 3), the energy of these transitions lie between those reported by these two authors. A discontinuity appears in the variation of E1 and E1 + Δ1 as a function of x.
Electron Excitation and Deexcitation Coefficients for the 3P2, 3P1, 3P0, and 1P1 Levels of Argon
Authors: Copley G. H. , Lee C. S.
Published: April 2011

Electron excitation and deexcitation coefficients have been measured for the first excited levels of Ar (3P0, 3P1, 3P2, and 1P1) using line absorption techniques to obtain excited state population densities in an Ar glow discharge in the pressure range of 0.2 to 10.0 Torr. In addition, several excitation transfer coefficients for excited Ar atom – ground state Ar atom collisions have been derived from the population density measurements and the results are in agreement with previous measurements obtained using pulsed Ar afterglows. The measured electron excitation and deexcitation coefficients yield velocity averaged cross sections for the various collision induced transitions. There is order of magnitude agreement with deexcitation cross sections calculated using a modified Thompson cross section and a Maxwellian distribution for the electrons. The assumption of a Maxwellian distribution is inappropriate for the calculation of electron excitation coefficients since the average electron energy is much smaller than the threshold for excitation of the first excited levels in Ar.
Velocity of Hypersonic Waves in Liquid Oxygen. Part II
Authors: Clouter M. J. , Kiefte H. , Morgan I. E.
Published: April 2011

Thermal Brillouin scattering techniques have been used to determine the velocities of hypersonic (0.2 to 3 GHz) waves in saturated liquid oxygen at temperatures from the normal boiling point (90.19 K) to the critical point (154.58 K). The results are in excellent agreement with corresponding ultrasonic (1.2 MHz, 10 MHz) velocities obtained from the literature, except for temperatures above about 148 K. In this region the hypersonic velocities are lower in magnitude than the ultrasonic velocities, the discrepancy being 4% at 150 K and increasing to 13% at 153.9 K. Since these discrepancies are substantially greater than the estimated experimental errors (±0.5% for the hypersonic velocities, ±0.05% for the ultrasonic velocities) it is concluded that saturated liquid oxygen exhibits a significant negative dispersion in the sound velocity at temperatures immediately below the critical point.
A Method for Calculating the Index of Refraction of Thin Films
Authors: Wohlgemuth J. H. , Brodie D. E.
Published: April 2011

A new method for determining the index of refraction from normal incidence reflection and transmission measurements has been developed. Several other methods are reviewed to explain why a new method is needed. The author's method used a thickness variational approach. For an accurate determination of n and k, the method requires normal incidence reflection and transmission measurements over a fairly broad spectral range for at least two different film thicknesses. These requirements are unavoidable for normal incidence methods.
The T3 Term in the Diffusion Thermopower, Applications to Pd, Pt, and Their Alloys
Authors: Muir W. B. , Zuckermann M. J.
Published: April 2011

The free electron thermopower is derived to order T3. We also obtain a useful approximate expression relating the coefficient of T3 in the thermopower to the coefficient of T2 in the residual resistivity of Pd, Pt, and some of their alloys.
A Model for the Excitation of Electron Aurora and Some Applications
Authors: Jones A. Vallance
Published: April 2011

An auroral model which has been found useful in the discussion of auroral spectra and excitation processes is described in detail. The model is similar to that of Rees and Jones and takes into account excitation by primary and secondary electrons, thermal electrons, and dissociative recombination. The growth of electron and ion concentrations, NO concentration, and electron temperatures are computed. Predicted intensities and their variation with atmospheric composition and primary particle energy spectrum are plotted and compared with observed values. The results given cover the N2+ first negative system, the N2 first and second positive systems, the O2 atmospheric and IR atmospheric systems, as well as the 5577 Å and 6300–6364 Å [O I] multiplets. Concentration height profiles and integrated emission intensities are given for N(2D), O+(2D), and O+(2P) as well as estimates of potential production rates from the N(2D)–O, N(2D)–O2, O+(2D)–N2, O+(2D)–O, N2(A3Σ)–O, N2(A3Σ)–NO, and O2+–NO energy transfer reactions.
Solutions des équations d'Einstein–Maxwell
Authors: Söler F. , Fugère J.
Published: April 2011

The solutions of the Einstein–Maxwell's equations are investigated for metrics that generalize that of Peres and Takeno for gravitational plane waves and such that the Lichnerowicz conditions are satisfied.
Transitions de phase dans une couche monomoléculaire sur un substrat liquide adhésif
Authors: Caillé Alain , Ågren Göran
Published: April 2011

We use a lattice model to characterize the state of a monomolecular layer of long and rigid molecules. The solutions are obtained using a mean field theory with only short range repulsion forces. The basic results are: (1) a stable nematic phase for a region of density above a minimum length to breadth ratio; (2) the transition between the nematic phase and the isotropic phase is found to be second order. The results are in excellent agreement with those obtained with a mercury subphase.
Isothermal and Frequency Dependent Perpendicular Susceptibilities of the Ising Model on the Cayley Tree
Authors: Horiguchi T. , Morita T.
Published: April 2011

The isothermal and frequency dependent perpendicular susceptibilities under zero external field are obtained for the Ising model on the Cayley tree. The difference between the isothermal and isolated susceptibilities is discussed. It is shown that two simple identities about the spin operators facilitate the derivation of the basic formulas for the perpendicular susceptibilities of the Ising model on a regular or irregular lattice.
Atomic Ionization Potentials Derived from Theoretical Calculations
Authors: Fraga Serafin , Saxena K. M. S. , Karwowski Jacek , Bray Brian
Published: April 2011

A table of all the ionization potentials of the elements lithium through krypton is presented.These values have been derived from the theoretical results obtained, within the Hartree–Fock method and including all the relativistic corrections, for the total energies of the ground states. The characteristics of the theoretical method are briefly outlined.Comparison with available experimental data establishes the excellent predictive value of the theoretical results.
The Excitation Energy of the First Excited State of 9Be
Authors: Fou C. M. , Gagne R. M. , Wu P. T.
Published: April 2011

The α particle spectra from the 11B(d,α)9Be reaction were analyzed for the first excited state of 9Be using three particle (n+α+8Be) kinematics with two particle final state interaction of the n+8Be system. A good fit was obtained assuming Ex = 1.70 ± 0.01 MeV and Γ = 0.20 ± 0.01 MeV.
Kinetic Theory–Memory Equation Approach to Nuclear Magnetic Relaxation in Molecular Gases. I. General Formulation for Homonuclear Diatomics
Authors: McCourt F. R. , Raidy T. E. , Festa R. , Levi A. C.
Published: April 2011

By considering nuclear magnetic relaxation in gases of homonuclear diatomic molecules from the point of view of kinetic theory and then applying the Zwanzig projection operator technique to the relevant kinetic equation, correlation function formulas are obtained for the longitudinal and transverse relaxation times T1 and T2 and for the intermolecular contribution to the chemical shift σ. The role of the transformation to a frame of reference rotating at the nuclear Larmor frequency is clarified and the various approximations inherent in both the usual correlation function and kinetic theory descriptions are carefully pointed out. Dispersion relations existing between T2−1 and σ when expressed as functions of the magnetic field strength are obtained and the conditions under which they may be expected to hold are discussed.
Investigation of a Magnetically Stabilized Helium Arc
Authors: Potočnik V. , Meyer J.
Published: April 2011

For verifying some theoretical predictions of light scattering from magnetized plasmas, a stable pulsed helium arc discharge in a magnetic field up to 5 teslas has been built. The arc has been investigated at filling pressures of 2 to 5 Torr and plasma currents between 1 and 5 kA. Plasma parameters were measured at a magnetic field of 4 teslas and a pressure of 3 Torr. At these values of the magnetic field and the filling pressure the arc is steady, approximately cylindrically symmetric up to a plasma current of 2.8 kA.Time dependence and radial distribution of the electron density and temperature have been determined from spectroscopic measurements, laser interferometry, and laser scattering. The latter two techniques were used successfully for the first time on a magnetically stabilized arc to measure the electron density and temperature in the hot core of the arc. The axial electron density is 1.2 × 1016cm−3 and is approximately constant over the arc cross section in the high temperature region as predicted by theory. The axial temperature is 145 000 K. Thus the arc design and the plasma properties are suitable for scattering experiments.
Measurement of the Abraham Force in a Barium Titanate Specimen
Authors: Walker G. B. , Lahoz D. G. , Walker G.
Published: April 2011

Accurate measurements of the Abraham density force have been conducted in a BaTiO3 ceramic for the first time. The measured torque amplitudes (in the order of 10−10 Nm) were in good agreement with the predicted values inside the error limits of 10%. This conclusively rules out Minkowski's unsymmetric momentum-energy tensor for material media at low frequencies.
Heating Rates for a Beat Frequency Laser Heated Plasma
Authors: Capjack C. E. , James C. R.
Published: April 2011

The heating of magnetized plasmas through the utilization of a beat frequency harmonic which is excited at a frequency near to that of a Langmuir mode in the plasma is examined. Heating rates are obtained for plasmas with temperatures in the range 1 eV to 10 000 eV. In addition, the effects of the plasma density and the mixing angle of the laser beams on the heating rate will be examined.
The Complex Dielectric Constant of Liquid Nitrogen in the Region 18 to 26 GHz
Authors: Reesor G. E. , Dagg I. R. , Mohabir S.
Published: April 2011

The complex dielectric constant of liquid nitrogen has been measured by a wave guide method in the frequency region 18 to 26 GHz; ε′ = 1.44 and tan δ = 5 × 10−5. The loss tangent is compared with infrared measurements.
Rotational Analysis of the Absorption Spectrum of Heavy Oxygen (18O2) in the Region 1200–1285 Å
Authors: Ogawa Masaru
Published: April 2011

The absorption spectrum of 18O2 has been photographed with a 6.65 m normal incidence type vacuum spectrograph in the 1070–1300 Å region. Rotational structures of the following bands have been analyzed; 1–0, 2–0, 3–0, and 4–0 of α1Σu+ ← X3Σg−; 2–0and 3–0 of β3Σu+ ← X3Σg−; and a strong band at 1246 Å. The upper state of the 1246 Å band is determined to have 3Σu− symmetry, and the transition is designated E3Σu− ← X3Σg−. These three upper states are Rydberg in character, with electron configuration (πu2p)4(πg2p)(3pπ). The observed rotational constants of the α1Σu+ and β3Σu+ states are nearly identical to those of the X2Πg state of O2+ to which these three Rydberg states converge. However, the rotational constant of the E3Σu− state, B1 = 1.3702 cm−1, is much smaller than the value B1 = 1.4764 cm−1 for the X2Πg state of 18O2+ estimated from the corresponding 16O2+ value. A brief discussion of this discrepancy is given.
Dynamic Jahn–Teller effect for an electronic E state coupled to the phonon continuum. II
Authors: Gauthier Napoléon , Walker M. B.
Published: April 2011

A coherent formalism describing the electron spin resonance of Jahn–Teller ions in 2E states in cubic crystals (the coupling being to the phonon continuum) is developed using thermal Green function techniques. The basic equation of the theory is a Wangsness–Bloch–Redfield equation of motion for the reduced density matrix for the combined spin and orbital degrees of freedom of the Jahn–Teller ion. The effective Hamiltonian and the t matrices describing phonon scattering processes are calculated by perturbation theory and several results for these quantities are given for both linear and quadratic orbit–lattice coupling. The effect of motional narrowing on the observed resonance spectrum of the 2E state is studied and results in agreement with experimental observations are found.
Effect of weak nonlinearities on the plane waves in a plasma stream
Authors: Seshadri S. R.
Published: April 2011

The effect of weak nonlinearities on the monochromatic plane waves in a cold infinite plasma stream is investigated for the case in which the waves are progressing parallel to the drift velocity. The fast and the slow space-charge waves undergo amplitude-dependent frequency and wave number shifts. There is a long time slow modulation of the amplitude of the electromagnetic mode which becomes unstable to this nonlinear wave modulation. The importance of using the relativistically correct equation of motion for predicting correctly the modulational stability of the electromagnetic mode is pointed out.
Pressure induced phase transitions of mercury chalcogenides
Authors: Lombos B. A. , Ghicopoulos B. , Bhattacharya S. , Pant B. C.
Published: April 2011

The nearest neighbor dependence of the pressure induced polymorphic phase transitions of mercury chalcogenides have been analyzed. An ionic and a metallic model were used to compute the lattice energies of both low and high pressure phases and the transition pressures of the HgSexTe1−x alloys. It was found that, contrary to the alkali halides, the transition pressure increases experimentally as well as indicated by theoretical calculations with increasing nearest neighbor distance. This is interpreted with the different behavior of the nearest neighbor distances related to the phase transitions. In the case of the alkali halides, although the dimensions of the unit cell decrease in going from the low to the high pressure phase, the nearest neighbor distances increase. However, in the case of the mercury chalcogenides, the trend concerning the unit cell is the same as in the case of the alkali halides, nevertheless the nearest neighbor distances decrease as a result of the pressure induced phase transition. This might clarify the inverse trend of the transition pressure as a function of the sizes of the anion sublattices, elicited by the nearest neighbor distances, in the case of mercury chalcogenides.
Transport properties of the ferromagnetic metals. II. Nickel
Authors: Laubitz M. J. , Matsumura T. , Kelly P. J.
Published: April 2011

We present new experimental results for the transport properties of Ni. In comparing these results to previously published values, we show that there exists a consistent group of experimental data which establishes reliably the transport properties of pure Ni from perhaps 30 to 1500 K. In the paramagnetic range (T > 630 K), these properties show three characteristic features: a positive slope of the thermal conductivity (which is equivalent to an electrical resistivity increasing less than linearly with temperature), a large negative thermopower, and a Lorenz function substantially larger than the Sommerfeld value, L0. In attempting to provide an explanation of these features, we have discovered that the model of Mott, wherein the electronic relaxation time is inversely proportional to the density of states, does not appear to be universally valid and, more importantly, that the observed properties cannot be consistently explained if we assume pure electron–phonon scattering. To achieve consistency, at least one other scattering mechanism has to be included, such as normal electron–electron scattering; this will be taken up in detail in a subsequent publication.
Theoretical relativistic oscillator strengths I. Transitions in principal, sharp, and diffuse series of Al I, Ga I, In I, and Tl I spectra
Authors: Migdałek J.
Published: April 2011

The oscillator strengths for the sharp, principal, and diffuse series in the spectra of Al I, Ga I, In I, and Tl I are calculated as well as the lifetimes of their lowest excited states. The wave functions that were used were calculated by employing a relativistic semiempirical method which included exchange effects. Very good agreement with the most reliable experimental data was obtained for the fik values in the sharp series as well as for the calculated lifetimes. The discrepancies in the diffuse series are ascribed to the failure of the one-electron approach in the case of strongly perturbed series. The observed deviations in the relative line strengths from the values predicted neglecting the spin–orbit interaction were also investigated. Some systematic trends in the calculated oscillator strengths that were found for the sharp and principal series appear to be corroborated by experimental data for the sharp series in the spectra of Al I, Ga 1, In I.andTl 1.
Theoretical oscillator strengths II. Transitions in principal, sharp, and diffuse spectral series of Al III, Ga III, In III, and Tl III spectra
Authors: Migdałek J.
Published: April 2011

A calculation is reported of nonrelativistic and relativistic oscillator strengths for the principal, sharp, and diffuse series, as well as some lifetimes, in the spectra of doubly ionized aluminum, gallium, indium and thallium. The wave functions that were used were obtained by employing a semiempirical approach which included exchange effects (the semiempirical [Formula: see text] method). Fairly good agreement was obtained with the available experimental and other theoretical data. A comparison of the nonrelativistic and relativistic oscillator strengths indicates that the influence of spin–orbit interaction of the optical electron, as well as other relativistic effects, is important in the case of even moderately heavy ions or atoms. Some systematic trends in the calculated oscillator strengths were found along the spectral series as well as along the sequence of homologous ions.
Spectral functions for gases: Test of approximations employing model kinetic equations
Authors: Müller Norbert , Hess Siegfried
Published: April 2011

Approximations to spectral functions obtained from model kinetic equations with two effective collision frequencies are tested for a special kinetic equation which can be solved exactly.
Raman spectral studies of molecular reorientation in liquid tetramethylsilane
Authors: Sunder S. , McClung R. E. D.
Published: April 2011

The contours of five Raman bands of liquid tetramethylsilane have been studied over the temperature range 178–350 K. Two bands were further analyzed to obtain the reorientational and angular momentum correlation times by removing the contributions from nonreorientational broadening and comparing the corrected Fourier transforms of the bands with the reorientational correlation functions calculated using the J diffusion limit of the extended rotational diffusion model. The agreement between the correlation times obtained from the analysis of the two Raman bands and those obtained from the nuclear relaxation study of liquid tetramethylsilane is satisfactory.
Elastic constants of the inert gas solids
Authors: Janzen A. , Leech J. W.
Published: April 2011

Calculations of c11, c12, and c44 for Ne, Ar, Kr, and Xe using a 12–6 potential in the quasi-harmonic approximation are presented and discussed. The method is based on an exact solution of the equations of motion for the homogeneously strained lattice. The need for employing consistently determined potential parameters is emphasized and previous calculations are criticized on this account.
Energy–momentum tensor in the microscopic plasma model
Authors: Lai C. S.
Published: April 2011

An energy–momentum tensor for the microscopic plasma model is constructed from the action integral by allowing for dynamics of special relativity. The energy density is then identified with the 44-component of the energy–momentum tensor. The result is compared with that obtained from an ad hoc method with the Legendre transformation. The Hamiltonian obtained can be used to tackle nonlinear problems in plasma physics.
On the dipole moments of excited singlet states of carbon monoxide
Authors: Fisher Nina J. , Dalby F. W.
Published: April 2011

The electric dipole moments of the B1Σ+, C1Σ+, and A1Π states of the CO molecule have been determined by observing Stark effects on the Ångstrom and Herzberg bands. We find the excited B and C states to have dipole moments of (1.60 ± 0.15) and (4.52 ± 0.35) D respectively. The upper limit for the dipole moment of the A1Π state is (0.15 ± 0.05) D.
Nonasymptotic behavior of developing turbulent pipe flow
Authors: Reichert J. K. , Azad R. S.
Published: April 2011

Detailed measurements of mean velocity U profiles, in the inlet 70 diameters of a pipe, show that the development of turbulent pipe flow is nonasymptotic. Experiments were done at seven Reynolds numbers in the range 56 000–15 3000. Contours of U and V fields are presented for two representative Reynolds numbers. A U component peak exceeding the fully developed values has been found to occur along the pipe centerline. The Reynolds number behavior of the peak position has been determined. Hot film measurements of the mean wall shear stresses in the inlet region also show a nonasymptotic development consistent with the mean velocity results.
Commentary on the NMR apparent phase transition effect in natrolite, fluor-montmorillionite and other systems: Generalizations when the Arrhenius law applies
Authors: Resing H. A. , Davidson D. W.
Published: April 2011

In situations where the NMR apparent phase transition effect occurs and the Arrhenius rate law is applicable, it has been shown that the mean activation enthalpy is roughly 37 times the temperature at which the mobile fraction is one-half. This and further generalizations have been applied to proton NMR line-shape analysis of water in natrolite and other systems; the mean activation enthalpy for water molecule diffusion in natrolite is estimated to be 18 kcal/mol.
Magellan: A balloon-borne collection technique for large cosmic dust particles
Authors: Wlochowicz R. , Hemenway C. L. , Hallgren D. S. , Tackett C. D.
Published: April 2011

A new technique for the collection of large cosmic dust particles from balloons is described. Two flights have been completed successfully. Preliminary results are given.
Size determination of spherical voids from the extrema of the Mie scattering intensities
Authors: Patitsas A. J. , Robillard F. , Kaye B. H.
Published: April 2011

Simple relations have been obtained, by numerical methods, between the diameter D of a spherical void (bubble) in a conducting medium of a given refractive index and the angular positions of the extrema of the Mie scattering intensities from the voids. The extrema are counted from the forward direction. These relations allow the determination of the positions of the extrema for a given diameter, or the reverse, without computational aids. The real part of the refractive index was varied from 1.25 to 15.00 and the imaginary part from 0.0 to 22.50. The size parameter α = πD/λ was varied in all cases from 4.00 to 24.00. The variable λ represents the wavelength of the incident radiation. These findings could thus be related to the scattering of microwaves by bubbles in water. Similar relations have also been obtained regarding the scattering of scalar waves by spherical voids. This corresponds to scattering of Schrödinger waves from complex spherical barrier potentials.
Electromagnetic scattering of an arbitrary plane wave by a wire mesh with bonded junctions
Authors: Hill D. A. , Wait J. R.
Published: April 2011

A doubly infinite set of linear equations for the currents has been found valid for a wire mesh with bonded junctions without imposing any junction conditions. However, the convergence of the solution is greatly improved by building junction discontinuity conditions into the current representation. Using such a modified solution, numerical results are generated to illustrate the dependence of reflection and transmission coefficients on various parameters.
Spectre d'émission du radical P2 : Etude des transitions C1Σu+–X1Σg+, A1Πg–X1Σg+ et B1Πu–A1Πg
Authors: Brion J. , Malicet J. , Guenebaut H.
Published: April 2011

Three electronic systems of the P2 radical have been photographed and studied in emission. Sixteen bands of the main system C1Σu+–X1Σg+ have been analyzed and a new perturbation for which the maximum is situated at J = 68 has been observed in the ν = 4 level of the C1Σu+ state. The study of the A1Πg–X1Σg+ transition has been extended by the analysis of the ν′ = 2 and 3 levels and by further observations in the ν′ = 1 level. Finally it has been possible to characterize a new transition B1Πu–A1Πg by the analysis of eight bands. Constants for the new B1Πu state have been calculated.
Comparison of approximation methods in one-dimensional many-body scattering theory
Authors: Coelho H. T. , Nogami Y. , Vallieres M.
Published: April 2011

The Glauber approximation, the optical potential method, and the resonating group method are applied to McGuire's scattering problem for which the exact solution is known. This one-dimensional problem deals with N particles of the same mass, interacting via a two-body delta function potential. The parameters of the model are chosen so that it simulates nucleon–nucleus scattering. When the 'finite N correction' is included, the optical potential method is found to be remarkably accurate, even at low energies. The validity of the optical potential and resonating group methods for the bound state is also examined.
Mélange de bandes au début de la couche 2s–1d
Authors: Desgrolard P. , Midy P.
Published: April 2011

A formulation in the strong coupling collective model framework with several valence nucleons is presented for odd mass nuclei. The position of the single nucleon in the shell is restricted only by the exclusion principle and a simple and correct treatment of the J2 term is proposed. Appreciable differences occur in the 2s–1d shell with respect to the previous treatments, which neglect the one-particle–two holes configurations. As examples, the 25Na, 27Mg, and 23Ne nuclei are discussed. The level schemes predicted by the model are in good agreement with the experimental data and compare favorably to recent shell model results.
On the moments of the pressure-induced spectra of gases
Authors: Poll J. D. , Hunt J. L.
Published: April 2011

It is pointed out that each component of a pressure-induced spectrum has two moments for which there are rigorous theoretical expressions. It is shown how these moments are related to the experimentally observed intensity. The theoretical expressions are given for the translational spectrum of inert gas mixtures and the translational, rotational, and vibrational–rotational spectra of homonuclear diatomic gases and of mixtures of these with inert gases. Examples of analyses in terms of these moments are given for the cases of the translational spectra of He–Ar, Ne–Ar, H2–Ar, H2–Kr, and H2–Xe, the rotational spectrum of H2, and the fundamental band of H2–He. Apart from the cases of He–Ar and Ne–Ar the results of these analyses are all new.
Infrared spectral moment and molecular multipoles in collision-induced absorption
Authors: Cohen E. Richard
Published: April 2011

An extension and generalization of the theory of multipolar interaction is developed which includes the effects of anisotropic polarizability, anisotropic pair distribution function, and orientational correlations. A formulation of overlap interaction is evaluated using a simple inverse power-law model. The spectral integral and the first moment of the absorption coefficient α(ω) are computed for a multicomponent gas. Anisotropic 'interference' terms couple the multipolar components so that the expressions are not simply sums over individual multipolar contributions. The theory presented here has been successfully applied in earlier published work to the determination of the multipole moments and molecular parameters of linear and tetrahedral molecules.
The spectroscopy of van der Waals molecules
Authors: Ewing George E.
Published: April 2011

The recent spectroscopy of van der Waals molecules is reviewed. Examples are presented from radio-frequency, microwave, Raman, infrared, and electronic spectroscopy. Diatomic van der Waals molecules (e.g. Ne2, Ar2, Kr2, Mg2) reveal a manifold of closely spaced vibration–rotation levels consistent with the small dissociation energies which are orders of magnitude less than for ordinary chemically bonded molecules. The (isotropic) interatomic potentials which define these molecules may be evaluated from their energy levels. Polyatomic van der Waals molecules (e.g. H2–Ar, FCl–Ar, (H2)2, (O2)2, (CO2)2) are classified according to the strength of the (anisotropic) intermolecular potential which tends to define their geometry. This classification depends on the nature of the coupling of the rotational angular momenta and leads to a labeling of the complexes as free rotor, weakly coupled, strongly coupled, or semirigid. The spectroscopic constants which are determined from the energy levels of diatomic and polyatomic van der Waals molecules can be used to better understand the intermolecular bonding which holds these molecules together.
Spherical tensor approach to multipole expansions. I. Electrostatic interactions
Authors: Gray C. G.
Published: April 2011

Using spherical harmonic expansions, the electrostatic field due to a given charge distribution, the interaction energy of a charge distribution with a given external field, and the electrostatic interaction energy of two charge distributions are decomposed into multipolar components. Extensive use is made of symmetry arguments. Comparisons with the Cartesian tensor method are also given.
Comparison of Lennard–Jones and Kihara potentials in the theory of collision-induced absorption and dielectric virial coefficients
Authors: Akhmedzhanov R. , Gransky P. V. , Bulanin M. O.
Published: April 2011

From the measurements of the binary integrated absorption coefficients or second dielectric virial coefficients, the molecular electro–optical parameters can be determined, provided the interaction potential is known. A comparison is made of molecular parameters, such as electric multipole moments, calculated by using the conventional Lennard–Jones and more realistic Kihara potentials. The Kihara potential is preferable for the polyatomic collision partners.
Collisional effects in compressed HD
Authors: Witkowicz T. , May A. D.
Published: April 2011

The Q branch in the Raman spectrum of compressed HD has been observed at room temperature and at 85 K. At low densities, collision broadening has been observed and the results analyzed using the theory of Gray and Van Kranendonk. Semiquantitative agreement is found between the observed and calculated broadening coefficients. At medium and high densities, motional narrowing of the Q branch occurs. Although qualitative agreement is found between the results and the theory of Alekseev and Sobel'man, a detailed comparison of the theoretical and observed profile shows that both frequency and intensity perturbations due to collisions have been omitted from the theory. Finally, a number of inconsistencies between the frequency perturbation observed by May et al. for H2 and the present observations are noted. These are not understood.
Theory of line shape in pressure-induced absorption
Authors: Birnbaum George , Cohen E. Richard
Published: April 2011

A quantum theory of line shape in pressure-induced absorption giving relatively simple results in closed form is developed. A flexible model correlation function satisfying certain general criteria is chosen and incorporated in a general quantum theory of absorption. Relations are derived for estimating the values of the time parameters in the correlation function in terms of known molecular parameters. The theory is applied to far infrared spectra: the translational spectrum of He–Ar, the well resolved S(0) rotational line of H2 at 77 K, and the unresolved rotational band of N2. In all cases, the theory fits the spectra and accounts for the spectral features.
Infrasound from a radar-observed meteor
Authors: McIntosh B. A. , Watson M. D. , ReVelle D. O.
Published: April 2011

The shock wave produced by the hypersonic entry of a sufficiently large meteoroid into the earth's atmosphere should be detectable at ground level. An array of microbarographs operated at Springhill Meteor Observatory recorded pressure waves on December 14, 1974, believed to be associated with a large meteor detected by the Springhill radars. The time interval between the radar observation and the detection of pressure waves is consistent with an acoustic travel time from the location of the radar echo. Estimates of the meteor mass from the radar echo duration agree with mass estimates calculated from the blast–wave theory of ReVelle. Because no azimuth information was available for the meteor to compare with direction of arrival of the pressure waves, the association is not absolutely certain.
The emission spectrum of SiN
Authors: Bredohl H. , Dubois I. , Houbrechts Y. , Singh M.
Published: April 2011

The emission spectrum of SiN has been reinvestigated under high resolution in the spectral region 3100–5600 Å. Besides the well known B2Σ+–X2Σ+, three new transitions have been analyzed, two 2Π–2Π and one 2Σ–2Π. These three transitions have a lower 2Π state in common which appears to be the lowest excited A2Π state. The B2Σ+–X2Σ+ transition has been reinvestigated and rotational perturbations have been found. The constants determined for the various electronic states are given.
New results on the D2Π and B′2Π states of the PO molecule
Authors: Ghosh S. , Nagaraj S. , Verma R. D.
Published: April 2011

A rotational analysis of the D–X and D′–X band systems of PO in the region 1900–2100 Å has been reinvestigated from an absorption spectrum taken at high resolution. A new ν = 1 vibrational level of the D2Π state of PO interacting with a new vibrational level of the D′2Π state has been studied in detail. Two other new vibrational levels, ν = 2 and 3, of D2Π have been recorded and studied in detail. A rigorous deperturbation of the D and D′ levels has been carried out. It has been shown that D′2Π and B′2Π are one and the same state of the PO molecule. A new band overlapped by the D′–X, 26–0 band has been attributed to the B2Σ+–X2Π transition.