bluuebunny/crossref_metadata_2025 huggingface dataset:
Finite-size effects in one-dimensional percolation: a verification of scaling theory
Authors: Greenspoon Stanley
Published: April 2011

The critical behaviour of the one-dimensional percolation problem is studied for a large, but finite, number of sites, N, in the light of finite-size scaling theory. The functions of interest, G(p), P(p), and S(p), are shown to be expressible asymptotically in a form consistent with scaling theory, in terms of a scaling parameter proportional to N/ξ, ξ being the correlation length. A plausible quasi-critical percolation probability for finite systems is proposed, and quasi-criticality is shown to occur at a unique value of the scaling parameter, in accord with a previously discussed law of corresponding states for finite systems. The rounding and shift exponents are found to be given by θ = λ = 1.
Stringlike solitons in toroidal coordinates
Authors: Williams J. G.
Published: April 2011

A classical field theory is studied in three space dimensions for the case in which the field variables range over a 2-sphere. Toroidal coordinates are found to be the most natural and lead to separation in the equations of motion. A number of finite energy solutions are indicated and correspond to structures extended in space.
Measurement of forces related to electromagnetic momentum in material media at low frequencies
Authors: Lahoz D. G. , Graham G. M.
Published: April 2011

Direct observation of the classical reaction force density −ε0μ0(∂E × H)/∂t with nonradiating fields (μ0H = constant) and inside a low permittivity nonmagnetic material has been carried out for the first time. Its magnitude seems to be ~25% larger than the theoretically predicted value although considerable experimental error (~20%) prevents a final appraisal of the significance of that discrepancy. Successful measurements of the force due to an external magnetic field on polarization currents inside two magnetite specimens at liquid He temperatures are also reported. Together these experiments give substantial credibility to the fine details of the so-called "Abraham force" in the low frequency range. However, possible observable differences arising from the alternative use of ε0μ0E × H or ε0E × B as the classical electromagnetic momentum in magnetic materials still remain within our experimental errors.
Uphill diffusion associated with a flux of extrinsic vacancies
Authors: Young D. J. , Delamotte E. , Kirkaldy J. S.
Published: April 2011

A phenomenological scheme and a corresponding kinetic model are developed to demonstrate the interactions between cation and extrinsic vacancy fluxes in ionic solutions. The solution examined consists of two monovalent species and one divalent species (with matching extrinsic vacancies) on the cation sublattice. It is demonstrated that the monovalent cations always tend to flow up the vacancy (or divalent cation) gradient and, in the event that a monovalent species is initially uniformly distributed, to subsequently flow up its own gradient. The magnitude of the un-mixing process is comparable to that obtained through thermodynamic interactions in metallic solutions.
Semiempirical prediction of atomic energy levels
Authors: Fraga Serafin
Published: April 2011

The predictive value of a simple and well-behaved expression is discussed on the basis of results for a considerable number of states of the Li through F isoelectronic series.
Proton spin relaxation spectrum of hydrogen gas at 77.5 K
Authors: Armstrong Robin L. , Kalechstein Wallace
Published: April 2011

The possibility of using proton spin relaxation measurements in hydrogen to detect the 'long time tails' of the associated correlation functions is discussed and an experiment described to look for such effects. A null result is obtained.
The effect of hydrostatic pressure on the Fermi surface of white tin
Authors: Perz J. M. , Templeton I. M.
Published: April 2011

The derivatives with respect to hydrostatic pressure of 12 extremal cross-sectional areas of the Fermi surface of tetragonal white (β) tin have been measured by the fluid helium de Haas van Alphen phase shift technique. The samples were carefully aligned in situ to have a crystal symmetry axis ([001], [100], or [110]) parallel to the magnetic field. The measured derivatives differ significantly from most values found previously by both direct and indirect methods; it is believed that the present work provides the first reliable comprehensive determination of these quantities. The present experiments also confirm the conclusions of magnetostriction experiments that there is a second orbit normal to [100] on the sixth zone surface not identified in earlier conventional de Haas van Alphen work, and that the third zone extremal areas normal to [001] are larger than previously accepted values determined in de Haas van Alphen studies.
Numerical determination of some generic nonlinear excitations in condensed matter physics
Authors: Currie J. F. , Bishop A. R.
Published: April 2011

Several classes of nonlinear, vector-field Hamiltonians in one spatial dimension are introduced, and numerical analyses of the kink or particle-like excitations supported by their associated classical field equations of motion are described. The generic character of these nonlinear mathematical problems in many branches of physics is stressed. Detailed results are presented for specific examples in statistical mechanics and condensed matter physics: an anisotropic XY model; interfaces in three-phase equilibria; and a complex order parameter Landau–Ginzburg model with discrete phase symmetry.
A note on some integrals useful in collision induced absorption
Authors: Gibbs P. , Hunt J. L. , Poll J. D.
Published: April 2011

A collection of tables of integrals useful primarily for the interpretation of collision induced spectra of gases has been deposited in the Depository of Unpublished Data of the National Research Council of Canada. This paper describes the nature of the integrals involved. These integrals and/or a listing of the Fortran program are available, at a nominal charge, from the Depository of Unpublished Data, CISTI. National Research Council of Canada, Ottawa, Ont., Canada K1A 0S2.
Energy of a spin- particle in a constant coloured magnetic field
Authors: McKeon Gerry
Published: April 2011

Using a method of calculation introduced by Schwinger, the radiative corrections to the motion of the spin [Formula: see text] particle in a constant coloured magnetic field are calculated. This is of interest as Batalin, Matinyan, and Savvidi have recently shown that the asymptotic freedom of coloured gauge fields implies that their energy density may be reduced by switching on a constant coloured magnetic field. It is found that the ground state of the spinor in this external field is not stable. Similar results for the vacuum polarization have been found by Nielsen and Olesen.
Generalized Schwinger boson realizations and the oscillator-like coherent states of the rotation groups and the asymmetric top
Authors: Gulshani P.
Published: April 2011

Various definitions of the coherent states of the angular momentum are shown to be special cases of the oscillator-like coherent states of the groups SU(2) and SO(3) obtained by Mikhailov on the basis of a generalized Schwinger boson realization of the angular momentum algebra. This realization is then generalized to that of the angular momentum algebra of an asymmetric top by means of a transformation from the Euler angles to the Cayley–Klein parameters. The oscillator-like coherent states of an asymmetric top, analogous to those of Mikhailov, are then constructed. It is, then, shown that Janssen's and Mostowski's definitions of the coherent states of a top are special cases of these.
About the equivalence of Abraham's and Minkowski's electrodynamics
Authors: Kranyš Miroslav
Published: April 2011

The old problem of the structure of the energy-momentum tensor of a polarized and magnetized elastic medium is investigated. It is shown that the Minkowski tensor in connection with Eckart's non-symmetric tensor—if one requires that the resulting tensor be symmetric—is equal to the sum of Eckart's symmetric tensor with the Abraham tensor. Both possibilities lead to the same energy-momentum tensor for a closed system. Consequently, the dynamical equations for both combinations are identical and the possibility of distinguishing between the two tensors by observing the Abraham force [Formula: see text] is out of the question.
Dielectric relaxation of some aliphatic ester molecules in solutions
Authors: Madan M. P.
Published: April 2011

The dielectric absorption of several aliphatic esters has been examined in the microwave region over a range of temperatures in n-heptane, cyclohexane, and benzene. The relaxation times and the thermodynamic parameters have been determined using the measured dielectric data. The values of the relaxation time for those solutions for which there are available known data agree well with other determinations. The relaxation times and the various molar activation parameters have been discussed in terms of dipole reorientation by molecular and intramolecular rotation. It would appear that the relaxation behavior of aliphatic esters is similar to that for other aliphatic molecules, such as aliphatic ketones studied previously.
Low-frequency scattering by a slit in an impedance plane
Authors: Hurd R. A.
Published: April 2011

A study is made of electromagnetic scattering by a narrow slit in an infinite plane. On the upper plane surface an impedance boundary condition is assumed; on the lower surface a different impedance condition obtains. Two types of incident wave are treated—a plane space wave and a surface wave. Expressions are found for the scattered fields and the field in the slit.
Beam-foil lifetime measurements for some 2p3nl terms of singly-ionized fluorine
Authors: Pinnington Eric H. , Gosselin Robert N. , Irwin David J. G. , O'Neill James A.
Published: April 2011

We have used the beam-foil technique in the wavelength region between 3500 and 4500 Å to measure the lifetimes of 10 terms in F II having the configuration 2p3nl, and also to demonstrate the usefulness of the ANDC method for overcoming the effects of cascade repopulation in these measurements. Our results are in good agreement with theory and with other experimental values.
Mean charged hadron multiplicities in high energy collisions — a new approach
Authors: Ghosh D. C. , Naha S. C. , Roy T.
Published: April 2011

A semi-empirical formulation for the energy dependence of multiplicity in p–p collision has been proposed. It has been found that experimental data for the multiplicity show a remarkable agreement with this formulation in the entire energy region 10 GeV to 106 GeV.
Cross section for the excitation of helium by protons
Authors: Ojha S. P. , Tiwari P.
Published: April 2011

Cross sections for the singlet excitation of helium by proton impact have been computed using the Vainshtein, Presnyakov, and Sobelman (VPS) method with peaking approximation. Transitions from the ground state to the n1P(n = 2, 3, and 4) states have been taken into account. The results are compared with other theoretical and experimental findings.
Non-linear self-consistent screening applied to metallic hydrogen
Authors: Whitmore M. D. , Carbotte J. P. , Shukla R. C.
Published: April 2011

Non-linear self-consistent screening of a proton by a high density electron gas has been used to find effective electron–proton potentials for metallic hydrogen for a number of densities and for both face-centered cubic and body-centered cubic structures. The resulting proton–proton potentials have been employed to calculate the phonons in the self-consistent harmonic approximation, following which the effective distributions α2F(ω) were evaluated in the plane wave, spherical approximation. From these, the superconducting transition temperatures Te and functional derivatives were found.Non-linear effects are seen to be important. For both structures, dynamical instabilities occur for rs ≥ 1.0, indicating densities higher than those predicted by linear theory are required. In addition, for the fcc case, Te is enhanced.Te is found to depend sensitively on the structure assumed; for the bcc case, it is very small.For fcc H. McMillan's equation overestimates Te by about 40%, even when λ = 0.5. Leavens' formula agrees with solutions of the Eliashberg gap equations to within about 10%.
Electrical transport in gadolinium iron garnet (GdIG)
Authors: Yadav Vijayee Ram , Lal H. B.
Published: April 2011

Thermoelectric power [Formula: see text] and electrical conductivity (σ) of Gd3Fe5O12 (gadolinium iron garnet GdIG) have been reported in the temperature range 500 to 1200 K. [Formula: see text] remains almost constant between 600 and 1100 K but it increases with decrease of temperature in accordance with the relation[Formula: see text]Conductivity changes by a factor of five near the ferrimagnetic Curie temperature (Te = 564 K). The log σ vs. T−1 curve also has a break at 900 K. Besides this jump and break the log σ vs. T−1 plot is linear and slopes of these lines correspond to activation energies of 0.55 eV for T < 560 K, 0.75 eV for the temperature range 575–900 K, and 0.92 eV between 900 and 1200 K. It has been concluded that electric conduction up to 1200 K in this compound is extrinsic. Between 575 and 1200 K it is due to hopping of holes from Fe4+ to Fe3+ sites and below 560 K it is due to the band conduction of holes in the valence (O2−, 2p) band.
Lattice relaxation around tetragonal and rhombic defects in alkali halides
Authors: Clayman B. P.
Published: April 2011

The relaxation of the crystal lattice around impurity pair defects in alkali halides is calculated based on a rigid ion model. Pairs with tetragonal symmetry—fourth nearest neighbors along the [001] axis—and those with rhombic symmetry—second nearest neighbors along the [110] axis— are both considered, for all cases where experimental evidence exists for resonant or gap modes. These are: NaCl with F−, Li+, and Ag+; KI with Cl−, Br−, Na+, and Rb+; KCl with Na+; and NaBr with Li+. Relaxation spaces with 72 ions (tetragonal) and 50 ions (rhombic) are used and results reported for all ions within the spaces. The nearest neighbor central force constants coupling the impurity ions and their nearest neighbors are calculated in the rigid ion approximation and the results compared with earlier dynamical model calculations. Because the dynamical models assumed that only one perturbed force constant was needed to characterize all the impurity–host interactions, and significant directional inhomogeneity of the force constants was a result of the present calculations, only qualitative comparisions could be made.
Extended high temperature low field expansions for the Ising model
Authors: McKenzie S.
Published: April 2011

High temperature low field expansions are derived from the free energy of the Ising model for several two- and three-dimensional lattices. These represent a considerable advance on earlier work. Expansions for the four-dimensional hypercubic lattice are also presented.
Shell-model calculations in the 4He system
Authors: Bevelacqua J. J.
Published: April 2011

Structure calculations for the 4He system are performed in both [Formula: see text] and [Formula: see text] model spaces. The results of these calculations suggest that a reasonable level spectrum can be obtained with the Sussex interaction if binding energy considerations are neglected. Imposing binding energy requirements leads to distortions in the level spectrum. The T = 1 levels and selected T = 0 levels are reasonably described by the bare Sussex interaction (b = 1.4 fm). The (0+, 0) 20.1 MeV level and (2−, 0) 22.1 MeV level are best described by the b = 1.80 fm and b = 1.60 fm Sussex interactions, respectively. Attempts to arbitrarily vary individual relative matrix elements do not improve the (0+, 0) spectrum. The resulting calculations suggest that an adequate description of the 4He level spectrum is not possible if a single oscillator length parameter is used for all levels. The results also emphasize the difficulty of performing structure and reaction calculations in a consistent manner, because different b values are required for binding, rms radius, or level considerations. The choice of b is not obvious and should be determined by solution criteria.
Shapes of optical emission lines from atoms excited by fast ion impact. II. Initial experimental results
Authors: Morgan F. J. , Dugan C. H. , Lowe R. P.
Published: April 2011

We present initial results of a new technique in which differential cross-section information is obtained by measuring the spectral line shape of emitted lines. We have measured the spectral line shape of the lithium resonance line at 670.7 nm (1s22s2S–1s22p2P) emitted following 5 keV Li+–He collision and compared it to the shape predicted on the basis of measured and theoretical cross sections using the method developed in paper I. Although broadening effects due to the particular experimental conditions used mask the details near the line centre, the shape of the wings of the line suggest that there is a significant amount of large angle scattering. The limitations of this new technique are discussed and it is concluded that, in the present case, cascade contribution to the population of the upper state is the most likely difficulty.
Investigation of level properties of 139La
Authors: Kulkarni R. G. , Andhradev K.
Published: April 2011

The excited states of 139La up to 1800 keV were studied by means of Coulomb excitation of 139La with protons varying in energy from 4.0 to 5.5 eV. The gamma-ray yields and angular distributions were measured with a Ge(Li) detector. The levels at 1715.0 and 1767.2 keV were Coulomb excited newly. The results of gamma-ray angular distribution measurements establish spin values of 3/2+, 9/2+, 7/2+, 5/2+, and 3/2+ for the 830, 1219.1, 1536.3, 1715.0, and 1767.2 keV levels, respectively. The reduced E2 and M1 transition probabilities were obtained for 11 transitions. The results were compared with the available theoretical calculations.
Kinematics of the central stars of the planetary nebulae
Authors: Varshni Y. P.
Published: April 2011

A study of some statistical properties of the transverse motion of the central stars of 62 planetary nebulae is presented. It is found that, at low values, the observed proper motion is almost independent of the distance.
Relaxation processes of quinoline, isoquinoline, and their mixtures
Authors: Madan M. P.
Published: April 2011

The dielectric absorption of quinoline, isoquinoline, and their binary mixtures has been studied in the microwave region over a range of temperatures in dilute benzene and n-heptane solutions. The relaxation times and the thermodynamic parameters for the activated state have been determined using the measured dielectric data. The results obtained have been discussed in terms of the molecular motion of the system. A relation has been proposed to represent the relaxation behavior of a system of two Debye-type polar components in a non-polar solvent. The relation has been tested by comparing the calculated values with those determined experimentally for a few systems consisting of similar, simple rigid polar molecules.
A possible mechanism for the behaviour of a p–n, II–IV amorphous heterojunction
Authors: Brodie D. E. , Moore C. J.
Published: April 2011

A phenomenological model is suggested for an amorphous p–n heterojunction. The forward bias currents are influenced by the large mobility decrease that occurs for majority carriers in extended states as they arrive at the junction region and enter hopping states. A zero-bias barrier exists but this increases with forward bias since the mobility mismatch initially produces a change in the space charge region width as well as a decrease in the average space charge density with increasing current density. At larger forward biases, the space charge region width tends to saturate and the average space charge density begins to increase.The reverse bias breakdown current is due to majority carrier tunneling. This model developed from the observed I–V characteristics is used to predict results that are compared with the measured current-temperature (at fixed bias) and bias-capacitance variations for actual devices.
Temperature dependence of the 59Co quadrupole coupling constant in K3Co(CN)6
Authors: Lourens J. A. J. , Smit E.
Published: April 2011

Expressions are presented for calculating the effects of bond-stretching and rotational modes of vibration on the temperature dependence of quadrupole coupling constants in crystals. Contributions to the motional averaging of the electric field gradient tensor arising from point charges, point dipoles, and overlap of closed wave functions are evaluated and the resulting expressions applied to analyse the temperature variation of the 59Co quadrupole coupling constant in K3Co(CN)6. Both stretching and rotational internal modes of vibration of the Co(CN)6 octahedron had to be taken into account to analyse the data. In particular, an intermediate frequency mode of wavenumber 414 cm−1 has been found to make a substantial and positive contribution to the shift in coupling constant arising from the low (~ 100 cm−1) and intermediate frequency (~ 400 cm−1) modes. The remainder of the shift (~ 90%) has been attributed to a rotary mode of wavenumber 26 cm−1. The extracted temperature dependence of this mode points to the possible existence of a structural phase transition in K3Co(CN)6 below 100 K.
High spin states in 96Tc populated through the (α,n) reaction
Authors: Mach H. A. , Johns M. W. , Thompson J. V.
Published: April 2011

High spin states of 96Tc populated by the (α,n) reaction using alpha beams from 13 to 27 MeV have been studied. Gamma-ray energies and intensities, gamma–gamma coincidence probabilities, gamma-ray angular distributions, and electron conversion coefficients were determined at 18 MeV. In addition, some results taken at 14 MeV are reported.The high spin structure observed in this work includes the following levels: 49.3(6+), 318.8(6+), 574.7(7+), 926.9(9+), 946.5(8+), 1062.1(8+), 1138.8(8+), 1447.2(9+), 1702.8(10+), 1861.6(9+), 1922.3(11+), 2147.5(11+), 2213.5(10(+)), 2317.2(12+), 2396.8(11(+)), 2599.0((13)+), 2642.4((14)+), and 3020.1(12(+)).These experiments also clarify and extend the information obtained by previous workers. In particular, evidence is adduced for low-lying states at 0.0(7+), 34.3(4+), 45.3(5+), 120.3(3−), 177.0(5+), 226.2(2−), 227.0(4+), and 254.3(3+).The work identifies many other states of intermediate energy.Attenuation coefficients for states in 96Tc are calculated using a theoretical model.
Hydrostatic pressure dependence of the Fermi surface of rhenium
Authors: Perz J. M. , Svechkarev I. V. , Templeton I. M.
Published: April 2011

The derivatives with respect to hydrostatic pressure of nine extremal cross-sectional areas of the Fermi surface of the hexagonal transition metal rhenium have been measured by the fluid helium de Haas van Alphen phase shift technique. The samples were carefully aligned in situ to have a crystal symmetry axis ([0001] or [Formula: see text]) parallel to the magnetic field direction, in order to minimize spurious effects which might be produced by tilting of the sample; precise values of the de Haas van Alphen frequencies have been measured for these symmetry directions. With the field along [0001], oscillations have been observed that correspond to a branch which appeared to vanish near this direction in previous de Haas van Alphen studies. Clear evidence has been observed of the degeneracy along the A–L line on the hexagonal face of the Brillouin zone.
Correlation of high latitude tropospheric pressure with the structure of the interplanetary magnetic field
Authors: Rostoker Gordon , Sharma R. P.
Published: April 2011

In the past decade there has developed a body of circumstantial evidence suggesting that terrestrial meteorology is influenced by plasma and magnetic field properties of the solar wind. In this paper we shall present evidence which strongly suggests that variations in surface pressure at high latitude stations ringing the Gulf of Alaska are correlated with changes in direction of the interplanetary magnetic field. We shall also present evidence that the changes in surface pressure may depend on whether the interplanetary magnetic field changes from pointing sunward to pointing antisunward or vice versa. We shall discuss the role that the magnetospheric electric field, which is heavily modulated by the interplanetary magnetic field, may play in influencing processes which lead to changes in terrestrial weather patterns.
Microscopic calculations for the 4He continuum
Authors: Bevelacqua J. J.
Published: April 2011

A detailed theoretical model for the 4He system is constructed within the framework of the dynamical R-matrix formalism of Lane and Robson. The internal states are expanded on a basis of properly symmetrized translationally invariant harmonic oscillator eigenstates including all states up to [Formula: see text] of oscillator excitation. Scattering results for the 3H(p,p), 3He(n,n), 3H(p,n), 2H(d,d), 2H(d,p), and 2H(d,n) reactions are presented. Phase shift calculations for the p + 3H and n + 3He channels suggest a (1+, 0) assignment for the 25.5 MeV level. Detailed scattering calculations are in qualitative agreement with measured results. The results are also compared with resonating group and field theoretic models. Although each model has its advantages, none is able to provide a complete description of the 4He system.
Etude à basse température des largeurs et des déplacements des raies rovibrationnelles de la bande fondamentale de H35Cl comprimé par N2, O2, D2 et H2
Authors: Houdeau J. P. , Larvor M. , Haeusler C.
Published: April 2011

Linewidths and shifts in the spectrum (v0→1 band) of H35Cl perturbed by N2, O2, D2, and H2 have been measured for different temperatures (at 298 and 163 K). The Sisam spectrometer resolution was 0.024 cm−1. The Anderson–Tsao–Curnutte theory has been applied to the linewidth calculations. For perturbation by N2 and O2, this approach is justified by the intensity of electrostatic interactions, and it leads to a satisfactory agreement with experiment, at least for lines of low rotational quantum number. On the other hand, the low value of H2 and D2 quadrupole leads to values of the optical diameter close to the kinetic diameter. A discussion shows then that a more realistic approach is needed in that case.[Journal translation]
Diffraction of a cylindrical pulse by a metallic half plane
Authors: Chakrabarti A. , Sastry V. V. S. S.
Published: April 2011

A direct transform technique is applied to the initial and boundary value problem involving diffraction of a cylindrical pulse by a half plane, on which impedance type of boundary conditions must be met by the total field. The solution to the time harmonic incident plane wave is deduced as a particular case of the general time-dependent problem considered here and we avoid the Wiener–Hopf technique which leads to very complicated factorization and which masks the role of the impedance factor Z′ (a small quantity) in the expression for the scattered field.
A semi-quantal approach to electron inner shell vacancy creation in nuclear alpha decay
Authors: Law J.
Published: April 2011

On alpha decay, an electron inner shell vacancy may be formed in the recoiling atom through electron excitation (which includes excitation to bound and continuum levels) or by electron transfer to the outgoing alpha. We introduce a semi-quantal model which treats the recoiling nucleus and alpha motion classically and the electronic transitions quantum mechanically. We have applied this to the K and L shell vacancy formation problem in the alpha decay of 210Po.
Atmospheric aerosol scattering to mass ratio
Authors: Harrison A. W. , Pi Rosaline
Published: April 2011

The combined operation of a spectronephelometer and a cascade impactor has been used to study the ratio of differential scattering coefficient (at 550 nm) and mass concentration at mass concentrations of less than 40 µg m−3. Detailed analysis of the mass size distribution impactor data assumed to be near lognormal yielded values of the bulk density in the range 1 to 4 g cm−3. Measurements made in May–June 1978 and in November–December 1978 gave substantially the same results indicating no seasonal variation in either aerosol density or scattering coefficient to mass concentration ratio for mountain and continental background clean air.
Infrared saturable absorption in benzene, chlorobenzene, and bromobenzene
Authors: Caudle George F. , Izatt Jerald R.
Published: April 2011

Nine different aromatic halogenated hydrocarbons have been used to Q switch and mode lock the CO2 laser. This paper presents experimental data pertinent to an understanding of saturable absorption in a subclass of these molecules, the monohalogenated benzene derivatives. These data include spectra of the pertinent absorption bands, intensity-dependent transmission curves, and typical pulse characteristics. Some implications of the experimental data for eventual theoretical modeling of pulse formation by these vapors are also discussed.
Collision-induced microwave absorption in gaseous mixtures of various rare gases at 2.3 cm−1
Authors: Dagg I. R. , Leckie W. D. , Read L. A. A.
Published: April 2011

Collision-induced microwave absorption has been observed at 2.3 cm−1 for the rare gas mixtures Ne–Kr, Ar–Kr, Ar–Xe, and Kr–Xe. The absorption coefficient has been measured at room temperature for density products up to 8000 amagat2 and for various density ratios. These results have been used in conjunction with those of the infrared region to determine more accurately the zeroth moment for each of the spectra and hence have allowed improved values for the induced dipole moment parameters for the exponential model. Upper limits to the absorption in He–Xe and He–Ar mixtures in the microwave region have also been established.
A study of the chlorine nuclear quadrupole resonance frequency spectrum in potassium hexachloro-osmate by Fourier transform methods
Authors: Mintz J. David , Armstrong Robin L.
Published: April 2011

A study of the chlorine nuclear quadrupole resonance spectrum of K2OsCl6 in the vicinity of the structural phase transition using Fourier transform techniques is reported. At high temperatures a single symmetric line spectrum is observed as expected from the high temperature cubic antifluorite structure. Below Tc = 45 K the two symmetric line spectrum characteristic of a tetragonal distortion is seen. At intermediate temperatures, 45 < T < 150 K the spectrum consists of a single asymmetric line. A detailed analysis reveals that for the single crystal sample the asymmetric line is composed of two symmetric components, a main line, and a weak satellite shifted −1.5 kHz relative to the main line. This feature is unaffected by changes in temperature near Tc. It is attributed to the influence of interstitial impurities on neighbouring chlorine ions. For the powder sample, the asymmetry is qualitatively different. A detailed analysis shows that the line is a superposition of three components. In addition to the two components present in the single crystal, a third, broad component develops as the temperature approaches Tc. This feature of the spectrum is the cluster induced order-disorder manifestation of the local dynamics. The most probable reason that this third component is not observed in the single crystal spectrum is because it is too broad due to a difference in the detailed dynamics of the two samples.
On the global scale electrodynamic coupling of high-latitude and low-latitude regions
Authors: D'Angelo N.
Published: April 2011

Ionosonde data from Dourbes (Belgium) and Lindau (Germany) show a correlation of the F layer critical frequency with the interplanetary sector structure in 1974. These data provide additional circumstantial evidence in support of recent results on the low-latitude extension of magnetospheric convection.
Thermodynamically self-consistent theories of simple liquids. II. A perturbation scheme for systems with purely repulsive forces
Authors: Hall Donald S. , Conkie W. R.
Published: April 2011

A parametrized perturbation scheme is derived for simple systems with purely repulsive forces. The parameter is chosen so that the pressure in the system found by differentiating the free energy is consistent with that found by integrating over the radial distribution function. Results of calculations for the equation of state of an inverse-12 fluid are presented and found to be in excellent agreement with Monte Carlo simulations. The use of the results of the self-consistent scheme as a reference system for the Lennard-Jones fluid is discussed.
Electronic polarizabilities, ionic radii, and repulsive potential parameters for diatomic alkali halide molecules
Authors: Shanker Jai , Agrawal H. B.
Published: April 2011

The electronic polarizabilities of ions in diatomic alkali halide molecules calculated using the Seitz–Ruffa energy level analysis are found to agree closely with those recently estimated by Brumer and Karplus utilizing the exchange perturbation theory. A sensible test of these polarizabilities has been presented by calculating the molecular properties like dipole moments. Ionic radii for alkali and halogen ions appropriate to diatomic molecules are determined using the relation between size and effective nuclear charges. The radii thus evaluated are found to be nearly additive and reproduce the internuclear distances within about ± 0.10 Å for all the alkali halide molecules except for RbF and CsF. An analysis of interaction energies in alkali halide molecules is presented by adopting two potential forms for the repulsive energy showing, respectively, the inverse power dependence and exponential dependence on internuclear distance. The additivity of repulsive potential parameters is discussed in the light of recent investigations. The results for the molecular constants obtained from the exponential form are in much better agreement with experiment than those estimated from the inverse power form.
Three-body calculations of elastic scattering and stripping of deuterons on 16O
Authors: Aytimur Tamer , Svenne J. P.
Published: April 2011

A calculation is presented in which a reaction of complex nuclei is approximated by a model three-body problem. The results of such a calculation, for elastic scattering and stripping of deuterons from 16O, are compared to the results obtained from conventional distorted-wave Born approximation (DWBA) calculations. Since severe limitations had to be imposed on the three-body calculation, for computational reasons, and the Coulomb force was neglected, the problem is to be considered a model problem. Experimental data were used to guide the selection of the two-body interactions, but the results cannot meaningfully be compared with data. A comparison of the three-body results to those given by the DWBA show qualitatively good agreement in the differential cross sections for both elastic scattering and stripping, but quantitative agreement is obtained only for the elastic scattering results. Polarization observables show no similarity between the two calculations. Several possible reasons for this discrepancy are discussed, but more work is needed to separate various contributing factors.
Far-infrared lasers pumped with tunable narrow band CO2-TEA lasers
Authors: Izatt Jerald R. , Mathieu Pierre
Published: April 2011

Progress in several important areas of far-infrared (FIR) laser research would be greatly facilitated by the availability of a tunable multi-atmosphere CO2-TEA laser with an oscillation bandwidth of ~ 100 MHz. The narrow bandwidth requirement is imposed by the dynamics of the FIR laser. Tunability is necessary because accidental coincidences between CO2 laser lines and absorption lines in FIR laser media are too rare to provide strong, efficient laser action across the full FIR spectrum. Tunable single longitudinal mode (SLM) pumping under appropriate conditions also shows promise of producing a broadly tunable Raman FIR laser. In this paper the pump laser spectral requirements are established by considering pertinent elements of FIR laser theory and the spectra of typical FIR laser molecules. Several techniques for tuning narrow-band CO2-TEA lasers are reviewed and their applicability to this problem is assessed.
Hanle effect in the singlet excited states of the alkaline earths
Authors: Kelly F. M. , Mathur M. S.
Published: April 2011

The Hanle effect in the singlet states of Sr, Ba, Mg, and Ca has been studied over a range of densities. The low density observations lead to an accurate lifetime measurement of the singlet excited levels, and calculation of the related oscillator strengths. The depolarization cross sections, [Formula: see text], for collision with ground level neutral atoms have been obtained from the high density data.
Calculation of the spectral transmission of the earth's atmosphere in the region of the NO gamma bands
Authors: Freedman R. , Nicholls R. W.
Published: April 2011

Realistic long path high resolution transmission spectra of the atmosphere have been calculated in the regions of the (0,0) and (1,0) NO gamma bands for zenith angles between 40 and 70° and for path lengths between 28.5 and 120 km. The transmission spectra have been folded onto the Harvard solar rocket spectra to provide spectral irradiances at 28.5 km which is a typical balloon float altitude. Such data have immediate application to the remote sensing of atmospheric NO from balloons and satellites.
Spectral distortion effects due to finite pulse widths in deuterium nuclear magnetic resonance spectroscopy
Authors: Bloom Myer , Davis James H. , Valic Marko I.
Published: April 2011

The quadrupolar echo Fourier transform technique effectively eliminates spectral distortion in deuterium nuclear magnetic resonance (2H nmr) spectroscopy due to the finite time required for recovery of the rf receiver following the application of an rf pulse. For broad 2H nmr spectra, the influence of the quadrupolar interactions during the rf pulses leads to another important distortion effect. An exact correction for this effect is calculated using the formalism of Vega and Pines. A comparison of the theoretical distortion correction factor with experiment is made and found to be satisfactory.
Electronic excitation in symmetric ion–atom collisions: Kr+ + Kr
Authors: Jones E. Grant
Published: April 2011

Cross sections are reported for reactions of Kr+ with Kr at collision energies below 50 eV (cm) to excite the KrI resonance radiation from the 5s[3/2]10 and 5s′[1/2]10 levels. Reaction occurs by the transfer of translational energy into internal energy and each reaction is characterized by a kinetic energy threshold. Significant effects on the cross section are observed arising from variation of the J-state of the reacting Kr+ beam. The reactions are interpreted as collisional excitation occurring by means of a potential energy curve crossing in the short-range interaction region.
The use of the electron paramagnetic resonance of Gd3+ impurity ions and infrared spectra to study the phase transitions in NH4Ce(SO4)2∙4H2O single crystals
Authors: Malhotra V. M. , Buckmaster H. A. , Bist H. D.
Published: April 2011

The 9.4 GHz electron paramagnetic resonance (epr) of Gd3+ impurity ions in NH4Ce(SO4)2∙4H2O single crystals has been studied at 97–304 K. The Gd3+ impurity ion is found to substitute for the trivalent lanthanide ion in two inequivalent magnetic complexes corresponding to the tetramolecular unit cell. The epr spectra at 304 K have been analyzed using an orthorhombic symmetry spin-Hamiltonian. The observation of resolved Gd3+ impurity ion spectra in the presence of paramagnetic Ce3+ ions has been interpreted in terms of a random modulation of the interaction between the Gd3+ impurity and Ce3+ host ions by rapid spin–lattice relaxation of Ce3+ ions. The 304 K spin–lattice relaxation time of the Ce3+ ions has been estimated from the impurity ion epr linewidths and is found to be consistent with an Orbach process. It has been shown for the first time that NH4Ce(SO4)2∙4H2O single crystals have a phase transition sequence[Formula: see text]The infrared spectra of NH4Ce(SO4)2∙4H2O were studied at 120 and 303 K and the results are reported.
Atomic ground state energies
Authors: Bhaduri R. K. , Brack M.
Published: April 2011

It is demonstrated that atomic Hartree–Fock binding energies may be reproduced with great accuracy (within about four parts in a thousand) by a scaled model system in which the electrons are noninteracting, and are bound in a bare Coulomb potential.
Nuclear structure dependence in analyzing powers?
Authors: Falk W. R.
Published: April 2011

Calculations of the angular distributions of the cross-sections and analyzing powers in the [Formula: see text] Al reaction have been made using microscopic form factors. A wide range of shapes of the microscopic form factors, simulating different degrees of configuration mixing in the nuclear wave functions, fail to provide angular distributions of the analyzing powers that agree with experiment for the 2.73 and 4.41 MeV, 5/2+ states.
Scattering patterns from thin optical fibres
Authors: Lit John W. Y.
Published: April 2011

The light scattering property of a thin optical fibre is studied theoretically. Plane polarized electromagnetic waves with their E-vector and H-vector parallel to the fibre axis are considered to fall perpendicularly on the fibre. Selected maxima and minima in the scattered light patterns are found to be very sensitive to the fibre parameters. The results may be used as a sensitive quality control of the fibre radius or refractive index while the fibre is being drawn.
Lattice dynamics of ammonia
Authors: Powell B. M. , Dolling G. , Pawley G. S. , Leech J. W.
Published: April 2011

The frequencies of selected intermolecular modes of vibration and libration in a single crystal of deuterated ammonia (ND3) have been measured by the technique of coherent inelastic neutron scattering, at temperatures of 20 and 95 K. The results are compared with the previous optical measurements at the Γ point, and with calculations based on two different models for the intermolecular potential function. A detailed assessment of these data leads to a set of mode frequencies for the Γ, R, and M points. The elastic constants are calculated from the measured acoustic mode dispersion curves propagating along the three major symmetry directions. The existing intermolecular force models are in good qualitative agreement with experiment, but significant discrepancies remain to be resolved by future theoretical refinements.
Measurement of the crossover E4 transition (2009.8 keV) in 46Ti
Authors: Fujishiro M. , Satoh Y. , Okamoto K. , Tsujimoto T.
Published: April 2011

The photonuclear reaction 9Be(γ,n) was used to measure the intensity I(2009.8) of the crossover E4 transition in 46Ti by an improved method. A point-like 46Sc source was used to provide the 46Ti. Neutrons generated by the 46Ti gamma rays were detected with BF3 counters. The observed intensity per decay of 46Sc was I(2009.8) = (1.3 ± 1.0) × 10−7, which agrees well with the previous estimate by Fluharty and Deutsch. From the present result the reduced transition probability B(E4)ex and the partial mean life-time τ(E4) of the crossover E4 transition between the 2009.8 keV, 4+ state and the ground state in 46Ti were estimated as B(E4)ex = (5.6 ± 4.9) × 10−99 e2 cm8and τ(E4) = (1.7 ± 1.3) × 10−5 s, respectively.
Basis states for equivalent electrons. I. States for the Lie group U(2l + 1) × SU(2)
Authors: Ross William R.
Published: April 2011

The antisymmetric Slater basis states for N equivalent electrons form the basis for an irreducible representation of U(4l + 2). When we consider the subgroup U(2l + 1) × SU(2) we obtain states which are eigenstates of the total spin operator. The basis states for the irreducible representation of U(2l + 1) × SU(2) are expressed in terms of the Slater basis states. General expressions are obtained which can easily be applied regardless of the number of electrons, the value of l, or the irreducible representation that is considered.
Photoeffect cross sections in Al, S, Cu, Zr, Ag, Sn, Ta, Au, and Pb at 31.7, 74.8, 81.0, and 145.0 keV, derived from total attenuation measurements
Authors: Puttaswamy K. S. , Gowda Ramakrishna , Sanjeevaiah B.
Published: April 2011

Photoeffect cross sections in Al, S, Cu, Zr, Ag, Sn, Ta, Au, and Pb at 31.7, 74.8, 81.0, and 145.0 keV are derived from the measured total attenuation cross sections reported here. The derived photoeffect cross sections are in good agreement with the theoretical values of Scofield.
Prediction of electron affinities based on the 1/Z expansion theory
Authors: Lai C. S. , Madan M. P.
Published: April 2011

Two sum rules between the nonrelativistic binding energies of neutral atoms and isoelectronic ions are proposed to calculate the electron affinities of the elements H through F. The contribution of relativistic corrections is taken into account. The agreement between the predicted and observed values of electron affinities is very satisfactory.
An investigation of the 35Cl(n,γ)36Cl reaction
Authors: Kennett T. J. , Islam M. A. , Prestwich W. V.
Published: April 2011

A detailed study of the neutron-capture gamma-ray spectrum for chlorine, above an energy of 1.6 MeV, has revealed a total of 234 transitions with intensity greater than 0.04%. Consistency tests indicate that the average energy uncertainty for the entire set of gamma rays is 0.1 keV. Data reduction was accomplished by invoking spectral deconvolution techniques with the result that many previously reported transitions were found to be multiplets. A decay scheme was derived by making use of both these new findings and the high energy precision attained for the transition energies. The proposed decay scheme accounts for more than 98% of the observed intensity and the energy of the levels included were found to have an average uncertainty of 0.08 keV. Based upon an error-free 15N neutron separation energy of 10 833.30 keV, the Q values for 35Cl(n,γ)36Cl and 37Cl(n,γ)38Cl were found to be 8579.82 (2) and 6107.85 (10) keV, respectively.
A note on the criteria for fitting functions to measured points
Authors: Daniels J. M.
Published: April 2011

Formulae are derived to indicate how well a fitted function represents a set of measured points and the significance of the difference between two fitted functions.
Electrostatique de systèmes cylindriques de révolution où le potentiel sur certaines parties de la frontière est un polynôme du second degré de la cote suivant l'axe
Authors: Berger Colette
Published: April 2011

The systems studied are equivalent to indefinite cylinders with rotationally symmetrical potentials. The analytical expressions for the derivatives of the axial potential with respect to z are given for two elementary systems called "Electrode" and "Interval." This analysis is also applied to one further elementary system in which the boundary potential is zero except in one region where its dependence on z follows a second-order polynomial. For a complex real system, the analytical expressions of the derivatives of the axial potential are obtained by superposition of elementary systems. This method renders possible a rapid calculation of the field, even for systems with large electrode separations. Furthermore, it may be used for the design of aberration-corrected systems.[Journal translation]
Zero-range distorted-wave Born approximation analysis of (p,t) transfer reactions
Authors: Bevelacqua J. J. , Prewett S. V.
Published: April 2011

Zero-range distorted-wave Born approximation calculations are used to investigate the systematics of two-nucleon transfer reactions. The shapes of the calculated 40Ca(t,p)42Ca(gs) and 208Pb(p,t)206Pb(gs) cross sections are relatively insensitive to details of the core plus two-neutron form factor, if the form factor tails have similar shapes. Studies of heavy targets such as 206Pb suggest a surface reaction mechanism, but lighter targets (16O and 40Ca) indicate that spatial regions beyond the target surface provide the dominant contribution to the (p,t) cross section.