bluuebunny/crossref_metadata_2025 huggingface dataset:
On the nature of the diffusion potential
Authors: Kirkaldy J. S.
Published: April 2011

The 'diffusion' potential concept is examined critically within the conditions imposed by Maxwell's equations and the Thermodynamics of Irreversible Processes. It is demonstrated that under the zero current condition during non-steady state diffusion the self-field associated with the diffusion potential gradient is due entirely to a diffusion-induced distribution of dipoles. The general failure to recognize that the charge associated with the field is due to dipoles has led to an improper use of Poisson's equation and to certain oft-remarked-upon paradoxes. The dipoles appear in systems where counter-current ion mobilities differ greatly. In seeking electroneutrality the ion trajectories become 'curved' in such a way as to generate an instantaneous dipole current and field. The magnitudes have nothing to do with the dielectric properties of the medium.It is demonstrated that the zero current condition represents a quasi-steady state of minimum entropy production. Such a state of stability can be sustained provided the process of relaxation of the field to the pure dipole state by real charge neutralization is fast compared with the relaxation process for the chemical potentials of the neutral salts in solution. The energetics of ionic solutions are usually such as to abet the neutrality condition during diffusion processes.
Laser fluorescence and high vibrational levels of 15NO2
Authors: Brand J. C. D. , Chiu P.-H. , Hoy A. R.
Published: April 2011

Resonance fluorescence of 15NO2 excited by narrow-band radiation of an Ar+ laser at 514, 495, 488, and 476 nm is reported and analyzed. The data are combined with published laser magnetic resonance and infrared measurements to obtain a set of vibration and vibration–rotation constants for the electronic ground state of this isotope.The fluorescence bands reported are a-axis polarized, corresponding to a transition moment [Formula: see text] between 2B2 and 2A1 basis states. Numerous anomalies in the vibrational and rotational structure of the fluorescence indicate that, in the region of the manifold probed by the laser, vibrational levels of the parent 2B2 basis state mix extensively with one another as well as with high vibrational levels of the 2A1 ground state.
The transport properties of rubidium, and electron–electron scattering
Authors: Cook J.G.
Published: April 2011

The electrical resistivity, thermal conductivity, and thermoelectric power of Rb have been measured between 40 and 300 K. Two of the samples were bare, to avoid thermal contraction difficulties; the softness of these samples necessitated further, calibration, measurements on a third sample in glass, just below the freezing point. The electrical resistivity values agree well with published values of Dugdale and Phillips. The Lorenz function, not previously examined in detail above 25 K, shows strong evidence of electron–electron scattering, of a strength intermediate to that calculated by Kukkonen for Thomas–Fermi screening, and for Geldart–Taylor screening. Such scattering appears to have affected the thermoelectric power as well.
The Newtonian theory of gravitation and its generalization
Authors: Rastall Peter
Published: April 2011

The classical, Newtonian theory of gravitation is generalized in two stages. First, a theory is constructed which is valid for a class of strong, static gravitational fields. This theory, which we call the newtonian theory, is compatible with all the classical tests of relativistic gravitation. The newtonian theory is then rewritten in a covariant, geometrical form and is generalized to give a complete theory of gravitation whose post-Newtonian approximation is in agreement with all observations.
The reaction 15N(e, t0) between 20 and 25 MeV
Authors: Uegaki J. , Asai J. , Leung M. K. , Murphy II J. J. , Shin Y. M. , Skopik D. M.
Published: April 2011

The differential cross section for the reaction 15N(γ, t0) at θlab = 90° has been obtained for excitation energies between 20 and 25 MeV by the measurement of a triton energy spectrum from the reaction 15N(e, t0)e′12C. A virtual photon analysis was used to extract the photodisintegration cross section from the electrodisintegration data. Comparison of this cross section to the cross section at lower excitation energies shows that the 15N(γ, t0) strength is concentrated in the region between 16 and 21 MeV. Comparison of the (γ, t0) cross section with those of other photodisintegration channels suggests an isospin separation energy of 6 MeV.
Calculations of the spin susceptibilities and their volume dependence for Li, Na, and K
Authors: Wilk L. , MacDonald A. H. , Vosko S. H.
Published: April 2011

For a range of lattice parameters the Kohn–Sham equations were solved self-consistently in the muffin-tin and local spin density approximations for Li, Na, and K metals. The solutions were used to evaluate the spin susceptibilities χp via the variational principle of Vosko and Perdew for two choices of χh, the spin susceptibility of an interacting homogeneous electron gas: (i) the RPA result due to Shastry, and (ii) the Keiser and Wu (KW) result. For Li and K the volume dependence and absolute values of χp are in excellent agreement with experiment whereas for Na the RPA seems to be better. Calculations for K over an extended range of volumes show that non-linearity in χp sets in for V/V0 = 0.9.
Thermalization of the ideal gas in a one-dimensional box
Authors: Morita T. , Fukui Y.
Published: April 2011

The time-dependence of the phase-space distribution function is studied in a model system of a one-dimensional ideal gas in which the velocity ν of a particle after each collision at the walls takes random values, governed by a given probability distribution function g0(ν). It is shown that the steady state, other than the trivial one in which all the particles do not move, can occur if and only if the integral[Formula: see text]converges. Calculations are made for two probability distribution functions g0(ν); the integral[Formula: see text]converges for one g0(ν) and it diverges for the other g0(ν)
Spectral theory of diffraction of electromagnetic waves by a strip in the plane interface of two semi-infinite media
Authors: Splunter J. M. van , Berg P. M. van den
Published: April 2011

The diffraction of a plane electromagnetic wave by a cylindrical strip in the plane interface of two semi-infinite media has been investigated. For both the case of E polarization and the case of H polarization, the scattered field is written as a continuous superposition of plane waves (spatial Fourier type of integral). The complex amplitudes of these waves are directly related to the spatial Fourier transform of the surface current on the strip. In order to determine the surface current, a relatively simple iteration scheme has been developed. At the numerical calculations we successfully take advantage of the presence of a Fast Fourier Transform procedure. Numerical results pertaining to the power flow density are presented at different locations and as a function of the width of the strip. Furthermore, the scattering cross section of the strip, as a function of the electromagnetic contrast of the different media, is calculated.
Effect of external static perturbation on radiative decay of a two-level atom
Authors: Srivastava R. P.
Published: April 2011

A two-level atom interacting simultaneously with an external static field is reinvestigated. Here, first the Hamiltonian of the atom and the external field is diagonalized and then the interaction of the radiation field is considered. This method yields, directly, the state populations for the atom, and the lineshape and linewidth of the spontaneously emitted radiation. The earlier result on the state populations by Bali and Higgins has been compared with the present work and found to be in good agreement. The line shape of the emitted radiation is Lorenzian and the halfwidth is found to be increasing with increasing external perturbation. For the case where the atom is initially in the excited state, the intensity of the emitted radiation decreases with increasing perturbation and finally reaches a saturation limit. However, when the atom is considered to be in the ground state, initially, the intensity increases with increasing perturbation and it again reaches a saturation limit at a large perturbation field.
The molecular beam electric resonance spectrum of OPF3
Authors: Meerts W. Leo , Ozier Irving , Dymanus Antoni
Published: April 2011

The molecular-beam electric resonance spectrum of phosphoryl fluoride (16OPF3) has been investigated. A hyperfine study of (K = 0) multiplets has been combined with earlier magnetic resonance data and chemical shift arguments to obtain four spin–rotation constants and two tensor spin–spin constants. The results (in kHz) are: [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text], dFF = −2.3(9), and dFF = 4.1(9). A study of molecular magnetic effects has yielded the two molecular g-factors [Formula: see text] and [Formula: see text] as well as the anisotropy in the susceptibility [Formula: see text]. The molecular quadrupole moment has been calculated. From a study of the Stark effect, the electric dipole moment has been determined for the ground vibrational state and for the (ν5 = 1) and (ν6 = 1) fundamentals. The results are: μ = 1.86847(10) D, (μ5 − μ)/μ = −3.49(4) × 10−3, and (μ6 − μ)/μ = −0.65(4) × 10−3. For each of these two excited vibrational states, the l-doubling constants qt, and DqJ(t) (t = 5,6) have been obtained. This work demonstrates that the molecular beam electric resonance method can be applied to symmetric tops with relatively large room temperature rotational partition functions by reducing the rotational temperature to a few degrees kelvin with the seeded beam technique.
Electron–electron scattering in potassium
Authors: Cook J. G.
Published: April 2011

The electrical resistivity ρ, thermal conductivity κ, and thermoelectric power S have been measured for two bare K specimens between 80 and 330 K. The data fully support the main conclusions of an earlier, preliminary study by Cook and Laubitz. The Lorenz function L = κρ/T does not approach the Sommerfeld value L0 with increasing temperature. Both the magnitude and temperature dependence of L–L0 indicate the presence of an added term Wee in the thermal resistivity, due to electron–electron scattering. Such scattering also affects S. It is shown that the data for K, together with published values of B = Wee/T for Na, Rb, and the noble metals, form a consistent picture of electron–electron scattering in the monovalent metals above the Debye temperature.
Drift velocity of holes in germanium and silicon
Authors: Nakagawa H. , Zukotynski S.
Published: April 2011

The displaced Maxwellian distribution function as it applies to semiconductors with lattice limited scattering is discussed. It is shown that good agreement between theoretical results and experimental data for the drift velocity can be obtained if the phonon coupling constants are lowered somewhat from their correct values. Calculations are presented for p-type germanium and silicon and it is shown that the key factor that must be considered in both materials is the non-parabolicity of the valence bands.
Unpaired forces in the study of lattice dynamics of thorium
Authors: Awasthi K. N. , Kushwaha S. S.
Published: April 2011

A phenomenological model that considers interaction between ions in terms of two-body (central) and three-body (unpaired) forces and evaluates the effect of electron–ion interaction through a screened coulomb potential is developed for studying the lattice dynamics of thorium. The model satisfies the symmetry requirement of a lattice and fulfils the condition of invariance under rigid body rotation. Computed phonon dispersion relations and (θD – T) curve for thorium are in reasonably good agreement with the corresponding experimental data.
Volume forces in simple metals
Authors: Taole S. H. , Glyde H. R.
Published: April 2011

Within the local pseudopotential model taken to second order, the metallic energy, U, is a sum of a volume dependent and a structure dependent term. Only the second term, expressed as a volume independent, effective ion–ion interaction, is usually retained for lattice dynamic calculations. Here we firstly evaluate the contribution from the volume dependence of U to the longitudinal elastic constants c11and c12 and the bulk modulus B for a variety of models. This contribution, Δbs, which is due to the volume dependence of the screening, was identified by Wallace, Brovman and Kagan, Pethick, and by Finnis but its magnitude is in dispute. We find Δbs is important and very model dependent, ranging from −10 to−50% of B in the alkali metals and Al (but is +50% in Pb for one model) depending on both the pseudopotential and screening employed. Secondly, the usual dynamical matrix is generalized to incorporate this volume dependence. The volume effects are important for long wave phonons only and for most practical purposes may be neglected otherwise. The volume contributions to the pressure and the deviation of the Cauchy relation are also evaluated suggesting that the observed deviation of the Cauchy relation does not provide a reliable estimate of Δbs.
The nuclear structure of 166Er
Authors: Panar J. D. , Burke D. G.
Published: April 2011

Two-quasiparticle states in 166Er have been studied using the 167Er(d,t)166Er, 167Er(3He.α)166Er, 165Ho(3He,d)166Er, and 165Ho(α,t)166Er reactions. Beams of 15 MeV deuterons, 24 MeV 3He2+, and 27 MeV 4He2+ particles were produced by the McMaster University tandem Van de Graaff accelerator. The reaction products were analyzed with an Enge split-pole magnetic spectrograph and detected with photographic emulsions. Angular distributions were obtained for the (d,t) and (3He,d) reactions for levels up to ~2700 keV in excitation energy, although selected peaks were investigated at somewhat higher energies. The interpretation of the data was performed within the framework of the Unified model, incorporating pairing effects. In the neutron transfer study, two-quasiparticle states formed by removing a particle from the predominantly 7/2+[633] 167Er ground state were investigated, whereas the proton transfer study dealt with two-quasiparticle states formed by adding a particle to the 7/2−[523] ground state of 165Ho. Several previous assignments have been supported and many new ones are proposed. Several other assignments proposed in an earlier proton transfer study have been found to be incorrect. Earlier observations that some levels were populated in both the neutron transfer and proton transfer reactions have been confirmed and extended. In addition, the observation in the (d,t) reaction of several states populated by l = 0 neutron transfers has been interpreted in terms of a complex mixing scheme involving the 7/2+[633] ± 1/2+[400] configurations.
Tensorial calculations in molecular spectroscopy
Authors: Féménias Jean-Louis
Published: April 2011

A strict quantum mechanical formulation of Van Vleck's concept of Reversed Angular Momentum is given. This generalization leads to a method suitable for the calculation of the matrix elements of all kinds of tensor operators in molecular physics. Applications and examples are described for the diatomic case. Various interactions—in the non-rotating or in the rotating molecule—are studied, and some intensity factors are derived in an original way. In all cases, the simplicity, generality, rapidity, and consistency of the method are tested and, where relevant, compared with other techniques.
Nonlinear magnetoacoustic waves in a weakly inhomogeneous plasma
Authors: Thirtha D. Govinda , Mittal M. L.
Published: April 2011

Nonlinear magnetoacoustic waves in a weakly inhomogeneous plasma are analysed by reductive perturbation method. One-dimensionai spatial variations are considered in the equilibrium state (density, temperature, and magnetic field) of the system. The governing equation turns out to be a modified Korteweg – de Vries equation which includes damping effects. It is found that the combined effect of the temperature and magnetic field inhomogeneities on the solitary wave amplitude is such that each inhomogeneity counterinfluences the other.
An analytical proof for the generation of higher harmonics due to the interaction of plane electromagnetic waves
Authors: Valluri Sree Ram , Bhartia Prakash
Published: April 2011

An analytical proof is given for the existence of higher harmonics in the Euler–Heisenberg Lagrangian for the limit of ultra-strong fields. The amplitudes of such harmonics are much greater than for the weak field case for the same wavelength. Experimental detection might be possible with the rapid development of electron synchrotrons and storage rings.
A speculation about effective range formulas applicable to s-wave scattering under long range polarization potentials
Authors: Paul Derek
Published: April 2011

Known effective range expansions for s-wave scattering of charged particles from polarizable systems fail to fit sets of accurately known phase shifts δ0 for e+–H and e+–He scattering as accurately as simple modified formulas. Formulas are given in which k cot δ0 is multiplied by a factor having a zero for each expected pole in cot δ0. The resulting fits are shown and a double series expansion is suggested as a generally fruitful formula.
Some observations on the use of reliability indices in LEED crystallography
Authors: Hengrasmee S. , Mitchell K. A. R. , Watson P. R. , White S. J.
Published: April 2011

A reliability index ([Formula: see text]) proposed for low-energy electron diffraction (LEED) crystallography by Zanazzi and Jona has been investigated by assessing its ability to compare experimental intensity versus energy curves with those calculated for different non-structural parameters. Included in the latter are the energy dependence of the real part of the inner potential for Cu(111), and the individual variations of the imaginary potential and the surface Debye temperature for Rh(111). Also an error has been corrected in one atomic potential used in our earlier work on Rh(100) and Rh(111), and this allows a resolution of the discrepancy found previously in the geometrical structures indicated by a band structure potential and a superposition potential for rhodium. The results here provide general support for the use of the index [Formula: see text]in conjunction with procedures frequently followed in LEED crystallography.
Structure determination of LixTiS2 by neutron diffraction
Authors: Dahn J. R. , McKinnon W. R. , Haering R. R. , Buyers W. J. L. , Powell B. M.
Published: April 2011

The crystal structures of the intercalation compounds of LixTiS2 are investigated by neutron diffraction for x = 0.12, 0.33, 0.67, and 1.0. The Li atoms are shown to preferentially occupy the octahedral sites in the van der Waals gaps of the host TiS2 lattice for all values of x and no evidence for three-dimensional Li ordering is observed.
An observation of the instantaneous optical auroral distribution
Authors: Murphree J. S. , Anger C. D.
Published: April 2011

An unusual picture which shows the entire auroral oval was obtained by the Auroral Scanning Photometer on the ISIS-2 satellite during a quiet period on December 16, 1974. This essentially instantaneous view showed the auroral distribution to be continuous with a remarkable smooth equatorward boundary through all local times, except at noon where emission rates fall below background. The instantaneous pattern departs significantly from the statistical auroral oval, but the intensity ratios I(5577 Å)/I(3914 Å) at different local times are generally consistent with what would be expected from statistical studies of particle precipitation. Data from this period show clearly the dangers in attempting to infer the state of the magnetosphere, or even the likely precipitation pattern in other sectors, from data gathered at a single longitude. The observations indicate that plasmasheet precipitation occurs around the entire auroral oval with the possible exception of the dayside gap.
Topologically stable solutions in an O(4) Yang–Mills, Higgs system
Authors: McKeon Gerry
Published: April 2011

The classical Euclidean field equations for an O(4) Yang–Mills, Higgs system are considered, under the postulate of invariance under combined space and gauge rotations. The topological stability of the solutions is discussed.
Positron annihilation in deformed Co–Ni alloys
Authors: Dannefaer S. , Kerr D. P. , Kupca S. , Hogg B. G. , Madsen J. U. , Cotterill R. M. J.
Published: April 2011

Positron lifetimes have been investigated in a series of deformed Co–Ni alloys in an attempt to identify the mechanism involved in the annihilation process at dislocations. Isochronal annealing measurements show that, although the mechanism is complex in the deformed alloys before annealing, a unique defect state may be attained which gives rise to a lifetime of 140 ps, This value is similar to the lifetime related to monovacancies suggesting that annihilation occurs at a vacancy trapped by a dislocation. The dislocation density was determined by transmission electron microscopy and the trapping rate per unit dislocation density was found to be 2 × 1015 s−1. The phase transition between the fcc and hcp structure for two of the alloys is shown to introduce defects.
Pressure dependence of elementary excitations in normal liquid 3He
Authors: Glyde H. R. , Khanna F. C.
Published: April 2011

The density and spin–density excitations in normal liquid 3He under applied pressure are described within a simple RPA model employing the Landau quasiparticle–quasihole interaction. Damping of the zero-sound mode to multi-quasiparticle–hole pairs is also included. The zero-sound mode energy is predicted to increase markedly with pressure while the quasiparticle–hole spectrum energy decreases with pressure. The paramagnon mode remains largely unchanged. Damping of zero sound also increases with pressure. This increase coupled with a decrease in coherent neutron scattering intensity from liquid 3He suggests the zero-sound mode will be more difficult to observe at elevated pressures than at zero pressure. In the present model the pressure dependence of the excitations follows directly from the pressure dependence of the Landau quasiparticle–quasihole interaction.
Four-term WKBJ approximation and its application to Varshni V and Lennard-Jones potentials
Authors: Kesarwani R. N. , Varshni Y. P.
Published: April 2011

An expression is derived for the fourth non-zero term in the WKBJ quantization condition. The four-term WKBJ approximation is applied to the Varshni V potential for obtaining the eigenvalues, and the relevant integrals are analytically evaluated. Numerical results are obtained for the Lennard-Jones potential, which is a special case of the Varshni V potential, and are compared to the quantum mechanical eigenvalues obtained by Kirschner and Le Roy for η = 50. It is shown that the inclusion of the fourth term leads to an improvement in the eigenvalues over the three-term WKBJ eigenvalues. The results also indicate that for calculating extremely precise eigenvalues for any given potential, a high-order WKBJ quantization condition provides a good alternative to direct numerical quantum mechanical calculations.
Microscopic treatment of some weak processes in the A = 14 nuclei
Authors: Lorazo B. , Goulard B.
Published: April 2011

A microscopic treatment of weak processes like the β-decay of 14C (ground state) or 14O (ground state) and the partial muon capture by 14N (ground state) to 14C (ground state) is presented in order to detect the possible importance of the mesonic exchange currents in these unusually inhibited processes. The study shows that this possibility could occur in the muon capture process associated with the total spin [Formula: see text] hyperfine state.
Structures of conserved currents and mass spectra for scalar fields: an approach to the generalization of the Goldstone theorem
Authors: Shintani Meiun
Published: April 2011

Considering the commutators between a scalar field and a conserved current, we shall clarify the connection between the mass spectrum for a scalar field and the structures of a current. For a special form of currents involving c-number functions, non-invariance of the vacuum under the corresponding transformation entails the existence of a massive mode. It is shown that once a type of currents is specified, the pole structures for [Formula: see text] depend only on c-number parts of Jμ(x). We shall show that the non-vanishing Goldstone commutator does not automatically imply the degeneracy of the vacuum state, and discuss the applicability of the Goldstone theorem.
Photovoltaic effect and temperature dependence of the energy gap in the In1−x GaxSb alloy system
Authors: Roth A. P. , Keeler W. J. , Fortin E.
Published: April 2011

The temperature dependence of the direct energy gap Eg in the In1−xGaxSb alloy system has been measured from 6 to 300 K using the photovoltaic effect as a tool of study. The temperature coefficients of Eg in the alloy were related in a simple way to those of the parent binary compounds. It is shown in particular that the bowing parameter in the Eg(x) equation varied very little between 6 and 300 K.
Effects of non-axial electric field gradients on the ferromagnetic state of amorphous rare-earth alloys
Authors: Hernandez H. , Ferrer R. , Zuckermann M. J.
Published: April 2011

We discuss the influence of non-axial electric field gradients on the ordered state of amorphous ferromagnetic alloys containing rare-earth atoms.
A Hamiltonian for non-Abelian phase factors
Authors: McKeon Gerry
Published: April 2011

A change of variables from the non-Abelian gauge field Aμa(x) to the associated phase factor at a fixed time[Formula: see text]is made in the Yang-Mills Hamiltonian. The result is a Schrödinger-like equation for the quantity U[Γ].
Optimum molecular constants and term values for the X2Π(ν ≤ 5) and A2Σ+(ν ≤ 3) states of OH
Authors: Coxon J. A.
Published: April 2011

Least-squares fits of 1618 A2Σ+–X2Π frequencies, 774 X2Π vibration–rotation frequencies, and 125 microwave frequencies have been made to effective 2Σ+ and 2Π Hamiltonians containing adjustable parameters for each vibrational level. The fitted parameters from each band, some of which included the microwave frequencies simultaneously, have been merged to obtain a set of 13 A ↔ X band origins and 91 single-valued parameters for A2Σ+, ν ≤ 3 and X2Π, ν ≤ 5. The set of parameters reproduces the experimental frequencies with residuals which on the average are only about 1.12 times larger than the estimated precisions of the data. Tables of term values calculated from the merged constants are reported for the two states.
The contrast variation of polychromatic speckle patterns at the far-field diffraction plane
Authors: Tomita Y. , Nakagawa K. , Asakura T.
Published: April 2011

The contrast variation of polychromatic speckle patterns at an arbitrary point of the far-field diffraction plane is studied theoretically and experimentally. Gaussian statistics are assumed for the formation of speckles. The average contrast of speckle patterns at the far-field diffraction plane is actually theoretically evaluated and experimentally measured for diffuse objects having a wide range of surface roughnesses under illumination of the polychromatic Gaussian laser beam. This contrast is found to depend strongly on the surface roughness of objects, the number of scattering cells within an illuminated area over the object, and a radial distance from the center of the far-field diffraction plane. Good agreement between the theoretical and experimental results is confirmed.
Removal of acceleration terms from the two-body Lagrangian to order c−4 in electromagnetic theory
Authors: Barker B. M. , O'Connell R. F.
Published: April 2011

Starting with the acceleration-dependent Lagrangian to order c−4 for two charged bodies (with e1/m1 = e2/m2) in electromagnetic theory, we show how to correctly convert the acceleration-dependent terms in this Lagrangian into velocity- and coordinate-dependent terms by a procedure that we call the method of the double zero. From the resulting velocity-dependent Lagrangian we easily find the corresponding Hamiltonian and corresponding Hamiltonian and Lagrangian in center-of-mass coordinates. We also give the Ostrogradsky Hamiltonian.
Cross section and thermonuclear reaction rates for the 58Ni(p,γ)59Cu reaction
Authors: Cheng C. W. , King J. D.
Published: April 2011

The yield from the 58Ni(p,γ)59Cu reaction has been measured by detection of annihilation radiation in coincidence from the decay of 82 s 59Cu. Both thin (600 μg cm−2) and thick (117 mg cm−2) targets have been used, the latter being thick enough to stop the proton beam at all incident energies. The cross section calculated from the thin target yield contains much structure and is in reasonably good agreement with previous studies. Thermonuclear reaction rates have been calculated from both thin and thick target yields for temperatures of interest in explosive nucleosynthesis. Both thin and thick target rates are in very good agreement with previous determinations but the thin target rates are, on the average, 35% higher than thick target rates. The reaction rate for T9 ≤ 2 is shown to be strongly dependent on a resonance at 931 MeV (center of mass) whose strength is not well known. A set of rates for T9 ≥ 2 for both ground state and stellar reactions based on thin target measurements is recommended and analytic fits to the recommended rates are given.
Nonlinear behavior of instabilities in diphasic flow in a heterogeneous porous medium
Authors: Pal D. S.
Published: April 2011

The nonlinear behavior of instabilities (fingers) in a specific oil–water displacement process, which includes the effects of capillary pressure in a heterogeneous porous medium, has been analysed from a statistical viewpoint. It is shown that, based on theories available for capillary pressure, the statistical model does not lead to any stabilization of the fingers.
Right handed current and two body hadronic charm decays
Authors: Kamal A. N. , Verma Ramesh C.
Published: April 2011

To the conventional four quark scheme with (V − A) × (V − A) interaction we add an admixture of a right handed current of kind [Formula: see text]. The consequences of the resulting new piece in the weak Hamiltonian of the form (V −A) × (V + A) to (D+,D0,F+) → 2P decays are investigated.
Monte Carlo study of the depth and lateral range of low-energy projectiles in solids
Authors: Latta B. M.
Published: April 2011

For heavy projectiles on light targets, the experimental measurements of mean-depth and of lateral-range straggle indicate discrepancies of up to 100% in the previous numerical solutions which are based upon a Thomas–Fermi interaction potential. In contrast, the present Monte Carlo (MC) results, which are based upon a solid-state Thomas–Fermi (SSTF) interaction, are in good agreement with experiment. The present SSTF mean-depth estimates are also in good agreement with estimates based on semiempirical potentials and with estimates based on Hartree–Fock–Slater interaction potentials. There remain small discrepancies between experiment and all theoretical estimates of the mean depth. In the case of the lateral-range straggle, the present MC SSTF results are in excellent agreement with experiment. The previous large discrepancies between theory and experiment are attributed, in part, to the choice of potential and, in part, to the numerical methods used to obtain the lateral-range straggle. In addition, the present MC SSTF calculations of the mean-depth and lateral-range straggle for equal mass and light projectile on heavy target collision pairs are in closer agreement with existing numerical estimates.
Zero-range distorted wave Born approximation calculations for the 68Zn(d,6Li)64Ni reaction at 27.2 MeV
Authors: Bevelacqua J. J.
Published: April 2011

The reactions 68Zn(d,6Li)64Ni(0+,g.s.) and 68Zn(d,6Li)64Ni(2+, 1.34 MeV) are investigated using the zero-range distorted wave Born approximation (ZRDWBA). ZRDWBA calculations indicate that the optical parameter set of Fulbright et al. provides a good representation of the transfer data, and that adjustments to Coulomb radii or form factor quantum numbers are not necessary. Relative strengths for the 0+ and 2+ levels are found to vary by a factor of two when reasonable changes to form factor geometries are made.
The lattice modes of CS2 and neutron scattering selection rules
Authors: Pawley G. S. , Dolling G. , Powell B. M. , Torrie B. H.
Published: April 2011

A very simple model for the lattice dynamics of CS2 is presented. This model is fully stable for a unit cell distorted by no more than 2% from the measured cell and gives good agreement with lattice mode frequencies obtained from optical studies. Coulombic forces appear not to be important for this structure. The molecular motion in modes for all the special points in the Brillouin zone is described through the use of an explicit notation. The group theoretical work of Grout el al. is extended to give the full selection rules for coherent inelastic neutron scattering. These rules show that certain modes can be measured with minimal interference from scattering from modes of different symmetry when certain experimental conditions are adopted, and therefore these rules will be of great use in the neutron scattering studies now in progress.
Mode-locking by an intracavity plasma. Part I. Linear model
Authors: Piché M. , Bélanger P. A.
Published: April 2011

In this first paper we develop a linear model for the simulation of laser mode-locking by an intracavity plasma. The model involves fast partial cut-off of the laser beam followed by a Doppler shift of the transmitted spectrum. We demonstrate how sharp discontinuities in non-resonant beams generate short pulses. Applications of that property are proposed. We also present numerical results indicating that successive Doppler shifts can be used to narrow the impulse response of a homogeneous gain medium.
Avoided-crossing molecular-beam spectroscopy of symmetric tops. I. Phosphoryl fluoride (OPF3)
Authors: Ozier Irving , Meert W. Leo
Published: April 2011

A new avoided-crossing technique using a conventional molecular beam electric resonance spectrometer has been developed for studying symmetric rotors. By means of an external electric field, two levels with different values of K are made nearly degenerate and normally forbidden electric-dipole transitions between the interacting levels are observed. Mixing matrix elements ηST with ΔK = ± 3 arise from the centrifugal distortion dipole moment μD and mixing terms ηHYP, with ΔK = ± 1, ± 2 arise from the nuclear hyperfine Hamiltonian. Explicit expressions for ηHYP are given in an Appendix. Many of these terms break the symmetry of both the rotational and nuclear spin parts of the wave functions. The avoided-crossing method is discussed in detail, with emphasis on its application to the measurement of (A0–B0). It is shown how the technique can be used to determine the perpendicular moment μD, as well as μJ, and μK, the constants which characterize the dependence of the parallel dipole moment μ on J and K, respectively. Other applications include the experimental investigation of the selection rules for the individual terms in ηHYP and the determination of the sign of the rotational g-factors [Formula: see text] and [Formula: see text].∙The method has been applied to phosphoryl fluoride (OPF3). It has been determined that (A0–B0) = 217.4987(44) MHz, μD = 5.856(20) × 10−6 D, μJ = −3.38(10) × 10−6 D, and both [Formula: see text] and [Formula: see text] are negative.
A unidirectional threshold switch
Authors: Brodie D. E. , Moore C. J.
Published: April 2011

Some properties of a unidirectional threshold switch are presented together with a suggested electronic model. The device consists of two amorphous semiconducting layers sandwiched between two aluminum ohmic contacts to form a heterojunction. One layer is p-type amorphous ZnTe and the other is n-type amorphous ZnSe. The diode will switch to a low resistance state only with a forward bias.
Dipole oscillator strength distributions and sums for C2H6, C3H8, n-C4H10, n-C5H12, n-C6H14, n-C7H16, and n-C8H18
Authors: Jhanwar B. L. , Meath William J. , MacDonald J. C. F.
Published: April 2011

Dipole oscillator strength distributions (DOSDs) have been constructed for ground state ethane, propane, n-butane, n-pentane, n-hexane, n-heptane, and n-octane. Each DOSD is constructed by using available experimental and theoretical photoabsorption cross sections and by constraining the resulting dipole oscillator strength data to satisfy the Thomas–Reiche–Kuhn sum rule and molar refractivity constraints. The latter were obtained using available experimental refractive index measurements of relevant dilute gases. The recommended DOSDs, and the values of integrated "band" oscillator strengths and the dipole oscillator strength sums Sk and Lk (for a variety of k values) obtained from them, are reported. The discussion includes an analysis of the accuracy of the results and a comparison with available literature values, which are scarce, for the dipole properties of the alkanes.
Infrared spectra of InSe
Authors: Jandl S. , Banville M. , Deslandes J.
Published: April 2011

The infrared spectra analyses of InSe with the independent oscillator model and with the factorized model give results consistent with the β polytype ([Formula: see text] space group) assignment. It is shown that only the independent oscillator model gives a consistent description of the spectra and provides direct evidence for a large dynamical charge contribution to the interactions.
Resolved hyperfine structure in the C–X electronic transition of VO. An internal hyperfine perturbation in the C4Σ− state
Authors: Hocking W. H. , Merer A. J. , Milton D. J.
Published: April 2011

New grating and laser excitation spectra of VO show resolved nuclear hyperfine structure in the lines of the F1 and F4 electron spin components in the C4Σ−–X4Σ−electronic transition. It is shown that the C4Σ− state has a sizeable hyperfine structure, with the Fermi contact parameter bF (the coefficient of I∙S in the magnetic hyperfine Hamiltonian) equal to −0.00773 cm−1. Another internal hyperfine perturbation, of the type described by Richards and Barrow for the ground state, occurs in the C4Σ−state near N = 5; the line doublings are consistent with the Fermi contact parameter derived from the F1 and F4 lines.
External emission dominance and polarization asymmetries in pion–proton bremsstrahlung
Authors: Picciotto Charles
Published: April 2011

Polarization asymmetries for pion–proton radiative scattering are calculated based on an "external-emission dominance" model, for incident pions of 298 MeV and various coplanar and noncoplanar laboratory angles. The sensitivity of asymmetries to the various features of the calculation may be used to test the ultimate validity of the model which has been very successful in describing the experimental data near the Δ(1232) resonance region.
The Clausius-Mossotti relation for anisotropic molecular fluids
Authors: Palffy-Muhoray P. , Balzarini D. A.
Published: April 2011

It is shown that in the interior of a uniformly polarized homogeneous anisotropic fluid there exists a family of similar surfaces, determined by the two-particle correlation function, having the property that the dipole field at the origin due to molecules within these surfaces is zero. The resulting Clausius–Mossotti relation contains a parameter, ηαβ, which is a measure of the anisotropy of the molecular distribution. These results are applicable to nematic liquid crystals.
Influence of nonlocality in the spin–spin interaction functional on the Pauli susceptibility of Li, Na, and K
Authors: MacDonald A. H. , Liu K. L. , Vosko S. H. , Wilk L.
Published: April 2011

Two suggested nonlocal approximations for the spin–spin exchange-correlation interaction functional of the spin-density functional formalism have been applied to the calculation of the Pauli susceptibility, χp, of the alkali metals. The nonlocal approximations were found to imply values of the density-functional Stoner parameter, I, typically ~ 3% lower than values implied by the more usual local approximation. This qualitative trend was found to be supported by comparison of available experimental values of χp with new more accurate theoretical values for the local approximation to χp.
Magnetic moments of JP = 1/2+ baryons in broken SU(8)
Authors: Verma Ramesh C.
Published: April 2011

Symmetry breaking effects on the magnetic moments of baryons are studied in the SU(8) framework. We obtain a low value of μ(Σ+) in agreement with a recent experiment. The transition moment [Formula: see text] seems to require isospin breaking, which also improves the overall fit to magnetic moments. Charmed baryon magnetic moments are calculated with and without isospin breaking.
Refractive index measurements and order parameter determination of the liquid crystal p-ethoxybenzilidene-p-n-butylaniline
Authors: Palffy-Muhoray P. , Balzarini D. A.
Published: April 2011

Using a simple new interferometric technique, the ordinary and extraordinary refractive indices of the nematic liquid crystal p-ethoxybenzilidene-p-n-butylaniline have been measured separately as a function of temperature. Changes in the refractive indices have been measured with an accuracy of ±0.005% and the absolute values with an accuracy of ±0.5%. Thermal expansivity data has been obtained by utilizing a specially constructed thermometer containing the sample. By using a recently developed Clausius–Mossotti relation for anisotropic fluids, the effective molecular polarizability and hence the orientational order parameter have been obtained from refractive index and density measurements as a function of temperature.
Effect of finite ion-temperature on ion-acoustic solitary waves in an inhomogeneous plasma
Authors: Shivamoggi Bhimsen K.
Published: April 2011

The propagation of weakly nonlinear ion–acoustic waves in an inhomogeneous plasma is studied taking into account the effect of finite ion temperature. It is found that, whereas both the amplitude and the velocity of propagation decrease as the ion–acoustic solitary wave propagates into regions of higher density, the effect of a finite ion temperature is to reduce the amplitude but enhance the velocity of propagation of the solitary wave.
Amplification of spontaneous emission and gain measurement in dye amplifiers
Authors: Efthimiopoulos T. , Garside B. K.
Published: April 2011

A comparison is reported of the observed spectral narrowing of amplified spontaneous emission from dye amplifiers with predictions from a dynamical model based on rate equations. This is employed to develop a generally applicable method of determining the unsaturated gain within the dye medium. Comparison is made with another technique for determining gain over the restricted pumping range for which it is applicable. The matching of theory to experiment is sufficiently sensitive that good values can also be determined for the wavelength dependence of the excited singlet state absorption cross section.
The absorption spectrum of Cl2 in the vacuum ultraviolet
Authors: Douglas A. E.
Published: April 2011

The absorption spectrum of Cl2 in the vacuum ultraviolet region has been photographed with sufficient resolution to allow rotational analyses of many bands. The separated isotopic molecule 35Cl2 and cooled absorption cells were used to simplify the spectrum. A band system associated with an ionic state has been observed in the 1330–1450 Å range. Many large perturbations in the system prevent the determination of the usual rotational and vibrational constants. Some progress has been made in the analyses of a few bands associated with Rydberg states.
Total and K-shell photoeffect cross sections at K-edges of Cu, Zr, Ag, Sn, Ta, Au, and Pb
Authors: Puttaswamy K. S. , Gowda Ramakrishna , Sanjeevaiah B.
Published: April 2011

Total attenuation cross sections, total and K-shell photoeffect cross sections, K-jump ratios, and total to K-shell photoeffect cross section ratios at the K-edges of the elements copper, zirconium, silver, tin, tantalum, gold, and lead are extracted from our earlier studies on total attenuation cross sections on these elements. These are compared with the latest and extensively tabulated theoretical photoeffect cross sections of Scofield and agreement within experimental uncertainty is observed. Further, empirical relations for K-edge cross sections and ratios are obtained, and the values of constants in these relations are tabulated. These empirical relations are found to reproduce the values to an accuracy better than one percent.
Measured Coulomb corrections to the pair production cross sections of Ta and Bi
Authors: Sherman N. K. , Ewart G. M.
Published: April 2011

The cross sections for production of electron pairs on Ta and Bi nuclei by photons of energies between 3 and 30 MeV were deduced from total cross sections for photon absorption. Comparison with pair cross section values calculated in the plane-wave approximation and corrected for screening gave experimental values of the further correction required to account for Coulomb distortion. Above 15 MeV the experimental values of the Coulomb correction differ from values calculated using a semi-empirical recipe due to Maximon and Gimm, but agree fairly well with a recipe due to Øverbø up to 20 MeV, where they begin to differ. Either of these Coulomb correction formulas combined with screening corrections calculated using relativistic atomic form factors allows the pair cross section of Ta or Bi to be calculated accurately enough to reproduce the total photon cross section to about 1%. Neither formula can be relied upon to determine an unknown photonuclear cross section to useful accuracy from a measured total cross section.
Infrared spectra of ZrSe3
Authors: Jandl S. , Deslandes J.
Published: April 2011

The infrared reflectivity and transmission on monoclinic ZrSe3 crystals for both polarizations parallel and perpendicular to the chains are measured. Eight phonons are observed and compared to previous infrared results.
Electron effective mass values in GaAsxSb1−x alloys
Authors: Devlin Paul , Heravi Hassan M. , Woolley John C.
Published: April 2011

Measurements of Faraday rotation and of infra-red plasma reflectance have been made at room temperature on n-type polycrystalline samples of GaASxSb1−x alloys. Hence effective mass values m00* for the bottom of the (000) conduction band have been determined. The experimental variation of m00* with x is compared with the predictions of various models, viz., (a) a simple Kane model, (b) the model proposed by Berolo et al., and (c) the model proposed by Hermann and Weisbuch. It is found that the model of Berolo et al. gives the best fit to the experimental data.
Examples of two point kinetic equations obeying the entropy principle
Authors: Grmela Miroslav , Salmon Jean
Published: April 2011

Qualitative properties of solutions of a two point extension of the Boltzmann kinetic equation and of solutions of the Frey–Salmon two point kinetic equation are investigated. Our attention is focussed on: (i) compatibility of the long time behaviour of solutions with equilibrium thermodynamics, (ii) the thermodynamic equation of state implied by the two point kinetic equations, (iii) one point kinetic equations whose solutions approximate well the solutions to the two point kinetic equations for large time, and (iv) transport coefficients implied by the two point kinetic equations.
Lattice dynamics of dinitrogen tetroxide
Authors: Andrews Bruce , Anderson Anthony , Leech John W.
Published: April 2011

Lattice dynamics calculations on the cubic crystal N2O4 are described. The model assumes rigid molecules with Lennard–Jones interactions between atoms. The six parameters of the model are optimized to fit the observed zone-centre frequencies, equilibrium condition, and estimated lattice energy. The form of the calculated eigenvectors and the measured relative Raman intensities of the librational modes are used to estimate the components of the polarizability tensor for the N2O4 molecule. Dispersion curves are presented for the (100), (110), and (111) directions of the Brillouin zone, and no imaginary frequencies are encountered.