bluuebunny/crossref_metadata_2025 huggingface dataset:
Diffraction by a half-plane with different face impedances – a re-examination
Authors: Hurd R. A. , Przeździecki S.
Published: April 2011

The problem of plane wave scattering by a half-plane with different face impedances is reexamined by means of the Wiener–Hopf–Hilbert technique. The mode of attack is altered somewhat from that employed in a previous paper by Hurd, and the analysis is more carefully done. We show that the same solution is obtained whether upper or lower branch cut formulations are used. We also show that our solution is identical to that of Maliuzhinets, and that it satisfies the principle of reciprocity.
An inverse scattering method in time-domain electromagnetics
Authors: Chaudhuri Sujeet K.
Published: April 2011

An inverse scattering model, based on the time-domain concepts of electromagnetic theory is developed. Using the first five (zeroth to fourth) moment condition integrals, the Rayleigh coefficient and the next higher order nonzero coefficient of the power series expansion in k (wave number) of the object backscattering response are recovered. The Rayleigh coefficient and the other coefficient thus recovered are used (with the ellipsoidal assumption for the object shape) to determine the dimensions and orientation of the object.Some numerical results of the application of this coefficient recovery technique to conducting ellipsoidal scatterers are presented. The performance of the software system in the presence of normally distributed random noise is also studied.
Propagation of a Z meson in a homogeneous magnetic field
Authors: McKeon Gerry
Published: April 2011

The propagation of a Z meson in a homogeneous magnetic field is studied in the context of the Salam–Weinberg model. One loop corrections to the Z propagator can contain charged virtual particles, leading to an effective interaction with a constant external magnetic field. Only the contribution of virtual charged fermions are considered in this paper.
Absorption intensity measurements of the first overtone band of CO
Authors: Chandraiah G. , Hébert G. R.
Published: April 2011

The absolute intensity A2–0 of the 2–0 band of carbon monoxide has been measured with helium and argon as pressure broadening gases at pressures up to 600 amagat. A separate band intensity value has been derived from the measurements of several P-branch line intensity data and the Herman–Wallis formula. The best value obtained is A2–0 = (2.11 ± 0.08) cm−2 amagat−1. The square of the rotationless matrix element, [Formula: see text] has been found to be (4.39 ± 0.02)10−5 D2, as estimated from the measured line intensity values.
The M.I.T. bag model and the pion
Authors: Frank Mariana , O'Donnell Patrick J. , Wong Brenden
Published: April 2011

The problem of the pion mass in quark models is studied in the M.I.T. bag model. A new value of the bag energy for the pion is obtained. It is shown that the pion mass is not given simply in the standard bag calculations. A nonzero pion mass seems to be a function of the quark mass, in agreement with spontaneously broken chiral symmetry. The pion decay constant is determined to be 94 MeV in excellent agreement with experiment.
Relativistic generalization of whistler mode modulational instability
Authors: Prasad R. , Gupta G. P. , Singh R. N.
Published: April 2011

The modulational instability of whistler mode waves interacting with relativistic plasma has been studied. The application of the Karpman and Krushkal criterion to the nonlinear Schrödinger wave equation gives the spectrum of modulationally unstable whistler mode waves. The effect of relativistic particles on the growth rate and frequency spectrum of modulationally unstable whistler mode waves has been discussed.
An analysis of the particle trajectories in spherical blast waves reflected from real and ideal surfaces
Authors: Dewey J. M. , McMillin D. J.
Published: April 2011

High speed photogrammetry has been used to measure the particle trajectories in the flows resulting from the interaction of two identical explosively produced spherical shock waves. It is postulated that the interaction simulated the reflection of a spherical shock from an ideal nonenergy-absorbing surface. The "ideal" reflections were compared with reflections from two types of ground surface. From the observed particle trajectories the particle velocities, gas densities, and hydrostatic, dynamic, and total pressures in the complex air flows behind the shock interactions have been computed. These flows are described as two dimensional fields at fixed times and as time histories at fixed locations. The Mach stem shocks at the ground surfaces were weaker than those at corresponding positions near the interaction planes, but the magnitudes of the flow properties in these waves decreased more slowly and, at later times, became greater than those in the waves at the interaction planes. Computed pressure–time histories were compared to measurements made using electronic transducers and good agreement was found.
The magnetic dipole a1Δg → X3Σg− transition in the oxygen afterglow
Authors: Amiot C. , Verges J.
Published: April 2011

The magnetic dipole a1Δ →X3Σg− transition has been observed for the first time during the recombination of 16O atoms in an afterglow. The spectrum of the 0–0 band has been recorded with a high resolution Fourier transform interferometer. Accurate molecular constants, obtained by combining ir and microwave data, are given for the a1Δg and X3Σg− (ν = 0) electronic levels.
Rotational and collisional contributions in the Rayleigh and Raman spectra of fluid N2
Authors: Sampoli M. , Santis A. De , Nardone M.
Published: April 2011

Rotational and rotovibrational spectra of fluid N2 at T = 119 K and ρ = 570 and 625 amagatare reported. Substantial agreement is found with a recent molecular dynamics simulation which takes into account all dipole–induced-dipole effects including the cross interference term betwen permanent and induced anisotropy. A procedure is described to derive the nonrotational contribution from the experimental spectra using a rotational model spectrum based on a parametrized memory function.The derived lineshapes (collision induced plus cross term) are in agreement with molecular dynamics results.
Radiation-induced infrared lines in solid hydrogens containing tritium
Authors: Souers P. C. , Fearon E. M. , Stark R. L. , Tsugawa R. T. , Poll J. D. , Hunt J. L.
Published: April 2011

We have observed three radiation-induced lines (A, B, and C) in the collision-induced fundamental infrared spectra of solid hydrogens containing tritium. These hydrogens are T2, DT, D2, HD, and HT at 7 to 9 K. The A line is about 100 cm−1 below the Q1(0, 1) of the corresponding hydrogens. The B line lies at 10 to 20 cm−1 below the Q1(0, 1). The weak C line occurs only in T2 and D2 at a position between the A and B lines. These lines are interpreted as being due to the effect of ions on the molecules of the host lattice (T2, DT, D2, HD, and HT). These ions are formed following the radioactive decay of tritium. The positions of the A and B lines are due to the Stark shift in the host molecules caused by the electric field of the ions. The intensity of the lines yields an ion concentration in pure tritium of the order of parts per million.
Determination of the collision-induced depolarized Raman light scattering cross section of the argon diatom
Authors: Barocchi Fabrizio , Zoppi Marco , Proffitt Michael H. , Frommhold Lothar
Published: April 2011

We report two independent calibrations of the argon diatom Raman light scattering cross section at 20 cm−1 shift (Stokes side), based on rotational Raman lines of hydrogen and nitrogen as an external reference standard. The precision is about 5% on an absolute scale, and the agreement relative to each other even better. The excitation wavelength is 5145 Å, but calibrations at 4880 and 4579 Å are seen to be consistent if the dominating factor 1/λ4 (λ = wavelength) is accounted for. Thus, a useful secondary standard for the calibration of similar spectra is obtained, and a long-standing question as to the absolute value of the diatom scattering cross section appears to be settled.
The influence of intermolecular interactions on the Kerr constant of simple liquids
Authors: Ladanyi Branka M. , Keyes Thomas
Published: April 2011

Our theory of the Kerr effect in nonpolar liquids, based on the dipole–induced dipole model of optical response, is applied to fluids of spherically symmetrical molecules. A sample shape independent expression for the Kerr constant K is derived. This expression is expanded in a generalized Y von-type series in powers of "cut out" dipole propagators. The two classes of interaction-induced terms in the series are due to, respectively, the pair polarizability correlations, and to the hyperpolarizability – pair polarizability cross correlations. The leading pair polarizability term is well known to be proportional to the depolarized light scattering (DLS) intensity. We show that the leading interaction-induced hyperpolarizability term is proportional to the first nontrivial term in the Y von series for the dielectric constant. Both of these similarities are exploited in order to deduce the behavior of K at liquid densities from DLS and dielectric constant measurements and computer simulations on rare gases. Contrary to what one might expect from the Kerr virial coefficient results, we conclude that the interaction-induced hyperpolarizability becomes relatively important at high densities. This is a result of the drastic decrease in the pair polarizability contributions in this density regime.
Simultaneous infrared transitions in N2 + SF6 and O2 + SF6 gaseous mixtures
Authors: Brodbeck C. , Bouanich J.-P. , Jean-Louis A.
Published: April 2011

The simultaneous transitions arising from the ν3 band of SF6 associated with the fundamental vibrations of N2 and O2 have been extensively studied. The integrated intensities, the bandwidths, and the frequency shifts of the maximal absorption have been examined as functions of the density of N2 or O2. A nonlinear effect on the integrated intensities resulting from changes in the density of SF6 was observed. The binary absorption coefficient deduced from experimental intensities has been compared with the absorption coefficient calculated by considering the theory developed by Ketelaar.
A calculation of the neon pair polarizability including correlation effects
Authors: Dacre Peter D.
Published: April 2011

Calculations of the pair polarizability of Ne2 at both the SCF and CI levels are reported. The calculations are made using the finite field method. Basis extension corrections are made at the SCF level. These corrections are found to have a large impact on the computed values of the trace. Agreement of the large R values (R > 8 a.u.) with the DID expressions is obtained.The CI calculations show that the anisotropy appears to be calculable from the SCF results by scaling. The trace is a more complicated quantity. Electron correlation terms are clearly quite important in the region of the potential well. Values of the second dielectric virial coefficient are calculated. Agreement with experimental values is not obtained. Comparison with the trace and anisotropies used in predicting lineshapes is encouraging.
Analysis of the far infrared spectrum of gaseous N2
Authors: Poll J. D. , Hunt J. L.
Published: April 2011

The far infrared collision-induced spectrum of N2 gas at 300 and 124 K is analysed using an empirical lineshape function. The theory of the collision-induced spectrum of N2 is developed and expressions are derived for the first and second spectral moments in the cases of quadrupolar, hexadecapolar, and for L = 1 and L = 3 overlap induction. The spectra are then reconstructed with various combinations of these mechanisms in order to determine the best values and probable ranges of the quadrupole and hexadecapole moments and the strength of the overlap moments. We find an excellent fit for a value of the quadrupole moment that agrees with that found by Buckingham, QB = −(1.09 ± 0.05)ea02, with overlap dipole parameters λ1 = ± 1 × 10−3ea0, λ3 = 1 × 10−3ea0, and an effective hexadecapole moment Φ = −(10.4 ± 1)ea04.
Density dependence of the collision-induced light scattering spectral moments of argon
Authors: Zoppi M. , Barocchi F. , Varshneya D. , Neumann M. , Litovitz T. A.
Published: April 2011

The zeroth and second moment of the collision induced light scattering in argon have been measured as a function of the density in the gas phase up to 530 amagat at room temperature and in the liquid phase near the triple point. The experimental results have been compared with molecular dynamics calculations in both phases assuming the dipole – induced dipole model and an empirical form for the interaction induced polarizability anisotropy which was previously derived from the dilute gas experiments. The overall agreement between the calculated values of the moments employing the empirical model of anisotropy and the experimental ones is very satisfactory. In particular, the value of considering both the moments for this comparison is pointed out.
Relaxation rotationnelle de H2CO due à la détente du gaz
Authors: Bokilo Roger , Chardon Jean-Claude , Guichon Daniel , Labrune Jean-Claude
Published: April 2011

We study the rotation–translation energy transfer on an expansive formaldehyde beam. On this beam, we measure the translational and rotational temperatures with RF spectroscopy methods. We can verify that we are dealing with isenthalpic expansion. Comparing experimental and theoretical results, we determine the cross section of rotation–translation energy transfer (σr = 23 Å2) for H2CO–H2CO collisions and the rotational coupling parameter [Formula: see text].
Density effects on the rotational lines of D2 in D2–Ar mixtures
Authors: Buontempo U. , Codastefano P. , Cunsolo S. , Dore P. , Maselli P.
Published: April 2011

The induced rototranslational absorption spectra of D2 dissolved in Ar have been measured at T = 164 K at different densities up to about 500 amagats. From the measured absorption spectra we have derived the profile of the single S(J) line in order to study the effects of the density. The obtained results show a density narrowing of the line confined in a small frequency region around the peak frequency.
Two-body dynamics in fluids as probed by interaction-induced light scattering
Authors: Balucani U. , Vallauri R.
Published: April 2011

The relative dynamics of particle pairs in fluids is investigated both theoretically and by simulation experiments. The physical implications of this analysis are important in all interaction-induced phenomena and illustrated in the case of the pair time correlation function relevant to collision-induced light scattering in atomic fluids.
Density dependence of light scattering from nitrogen: Permanent and collisional effects and their interferences
Authors: Bérrué J. , Chave A. , Dumon B. , Thibeau M.
Published: April 2011

The light scattering from gaseous nitrogen at 310 K and pressures up to 440 bar is studied; the depolarization ratio versus the density is plotted. A theoretical calculation taking into account the light scattered from the permanent polarizabilities, the collisional ones, and their interferences is given. The agreement with the experimental data is rather good.
Vibrational dephasing in liquids: analogy with molecular electronic lineshapes
Authors: Gelbart William M. , Beswick J. Alberto , Delgado-Barrio Gerardo
Published: April 2011

In a liquid of diatomics, the intramolecular vibration is always much faster than the motions associated with the molecular centers of mass. This natural separation of time scales suggests that an adiabatic (Born–Oppenheimer-type) approximation should be useful in describing the dephasing (frequency modulation) of intramolecular vibrations in liquids. In this paper we use a generalization of the Lennard-Jones–Devonshire cell model to derive an effective potential for the translational–rotational–vibrational motion of a diatomic in the presence of its nearest neighbors. This allows for both approximate (e.g., adiabatic and crude-Born–Oppenheimer) and exact solutions for the energies and eigenfunctions of the coupled molecule–solvent systems. We use these solutions to evaluate the "golden rule" expression for the isotropic Raman lineshape associated with the fundamental vibrational transition. Even though our treatment is fully quantum-mechanical (without any explicit appearance of the time), natural definitions of the slow and fast modulation limits can be introduced. These provide contact with the more familiar semiclassical descriptions of vibrational dephasing. The physical mechanisms underlying the Raman linewidths are discussed in terms of "hot-band sequence congestion" and "Franck–Condon progressions," in full analogy with the case of vibronically broadened electronic bands. We also use the cell model to obtain a priori estimates of the collision-induced contributions to the Raman lineshape. More quantitative treatment of these effects, however, requires detailed information (which is not yet available) on the internuclear distance dependence of diatomic polarizability tensors.
Lineshapes and dipole moments in collision-induced absorption
Authors: Birnbaum George , Brown Michael S. , Frommhold Lothar
Published: April 2011

Wave mechanical lineshapes of collision-induced absorption spectra are computed for binary mixtures of argon with helium, neon, and krypton using theoretical dipole moments as input. Comparison with measured spectra shows satisfactory agreement except for the neon–argon mixture, for which either theory or measurement is seen to be in substantial error. Empirical models of the collision-induced dipole moment which reproduce the experimental spectra more closely than the fundamental theory are also given. Best agreement between computed and experimental lineshapes is obtained when potential models which are accurate in the repulsive region are used.
Détermination expérimentale des coefficients du viriel de la réfractivité des gaz : étude de l'argon
Authors: Coulon R. , Montixi G. , Occelli R.
Published: April 2011

A spherical Fabry Perot interferometer is used to determine the refractive index of argon to a few hundred bars, with a better accuracy than those obtained in preceding experiments.The first and second refractivity virial coefficients have been determined. Measurements have been made for eight wavelengths in the visible spectrum between 4359 and 6329 Å. A value of the third coefficient is given for the first time.Comparisons are made with preceding published values, and with values of dielectric virial coefficients.
Exact results for light scattering by dense systems of isotropic particles: How good is the DID model
Authors: Keyes T. , Madden P. A.
Published: April 2011

An exact, computationally convenient, expression for light scattering by a dense lattice gas is presented. It is shown how the exact theory can be used as a benchmark to test the assumption always made so far, that "pair" or "double" scattering is the dominant mechanism for depolarization by simple liquids. The tenability of the dipole – induced dipole model may be determined by the outcome of the indicated test.
Intensity and dipole correlation functions for the ν3 band of compressed OCS
Authors: Thanh Nguyen-van- , Bouanich J.-P. , Rossi I. , Strapelias H.
Published: April 2011

The IR spectrum of the ν3 band (4.85 μm) of gaseous OCS has been investigated along the liquid–vapor coexistence curve for temperatures varying from 268 to 358 K and densities up to 80 amagat. Measurements of integrated intensities are also reported at room temperature.The dipole moment autocorrelation functions (ACF) deduced from the spectra of compressed OCS are analyzed in terms of a collisional model derived from the impact approximation and in terms of Gordon M and J diffusion models developed classically as well as the semi-classical M diffusion model. For the collisional model which implies uncorrelated rotational levels, a discrepancy between predicted and observed ACF's is noticeable from about 15 amagat. The M and J diffusion models agree well with the experimental ACF's only up to 40 amagat.
Molecular reorientation in sodium hydrosulfide: a deuterium nmr study
Authors: Jeffrey Kenneth R. , Wasylishen Roderick E.
Published: April 2011

Deuterium nmr provides a unique opportunity to verify that the molecular motion in sodium hydrosulfide, NaSH, in the trigonal phase is the flipping of the SH− ion between two positions parallel and antiparallel to the trigonal axis. Measurements of the spin–lattice relaxation time show that motion of the hydrosulfide ion is not influenced substantially by deuteration. Measurements of the deuterium nuclear quadrupole splitting, ΔνQ, over the range of temperatures where the correlation time, τc, describing the motion changes from [Formula: see text] show little change. The molecular motion of the SD− ions must, therefore, not change the deuterium quadrupolar interaction and 180° flipping of the SD− ion is the only reasonable model which fits this criterion.Spin–lattice relaxation times have also been measured in the high temperature cubic phase. At 376 K, τc was found to be 0.40 ps in agreement with neutron quasielastic scattering measurements.
On a gauge-generalization of a nonlinear σ-model with nonvanishing Hopf invariant
Authors: Kundu A.
Published: April 2011

A field model in real space–time with the field functions taking values in S2 and interacting with a gauge field is proposed. An estimate from below through the Hopf invariant is found for the Hamiltonian of the model. The presence of mass terms in the model, which guarantees the exponential vanishing of the basic and the gauge fields at large distances, is shown to be essential for the existence of an energy bound. The Hopf invariant, given in an intermediate S3 manifold, and the structure of the solutions are studied.
Spectral distribution of scattered light by fluid mixtures of correlated atoms and molecules
Authors: Kielich S. , Bancewicz T. , Woźniak S.
Published: April 2011

A stochastic theory of the spectral distribution of light scattered by mixtures of atoms and molecules, colliding in time and space, is proposed. New time-correlation functions C(0)(t) and C(2)(t) are introduced describing respectively the statistical microscopic mechanisms of isotropic and anisotropic coherent scattering, related with changes in the first and second perturbation of the molecular polarizability tensor due to the long-range fields of induced molecular electric multipoles. In this way, not only anisotropic but also isotropic scattering is shown to have a rotational spectral structure due to orientational motions and angular collisions of the polar molecules. The hitherto not considered cross approximations 0,1 and 0,2 of the functions C(0)(t) and C(2)(t) involve the first power of the dipole–quadrupole, dipole–octupole, and quadrupole–quadrupole tensors thus permitting first determinations of the signs of the successive multipolar molecular polarizabilities.
A discrete method of constructing central and angular-momentum dependent potentials
Authors: Hooshyar M. A. , Razavy M.
Published: April 2011

For a central potential the Schrödinger equation for the lth partial wave is first transformed to a differential equation which depends linearly on l, and then the latter form is approximated by a difference equation. The structure of this difference equation is such that it makes it possible to arrive, in a natural way, at a Thiele's interpolation formula for the logarithmic derivative of the wave function outside the potential, which is related to the discrete form of the [Formula: see text]-matrix. If the numerical values of the [Formula: see text]-matrix, at a given energy, are known for N partial waves, then the found interpolation formula can be used to determine the potential at N equidistant points. This method, in a sense, complements the Newton–Sabatier method since it works better for low energy scattering. It can easily be generalized and applied to the problems where the potential depends on angular momentum, the example of inverse problem for spin-orbit interaction has been studied as an application of this method. Numerical results are given for a number of potential models.
The electric dipole moment of the state of thioformaldehyde
Authors: Goetz W. , Moule D. C. , Ramsay D. A.
Published: April 2011

The Stark effect on the [Formula: see text] system of H2CS has been investigated. An analysis of the Stark broadening of the lines in the pP3 branch with J″ = 3–8 yields a value of μ′ = −2.2 ± 0.3 D. The large decrease in dipole moment on excitation (μ′ = −3.85 D) is consistent with the large change in dipole moment which has been predicted for the analogous transition in H2CO.
Magnetic-shear stabilization of high-frequency drift waves
Authors: Shivamoggi Bhimsen K.
Published: April 2011

Stability of high-frequency drift waves in a plasma slab (consisting of cold ions and hot electrons) subject to a sheared magnetic field is studied. The method due to Pearlstein and Berk is used. It turns out that Antonsen's method does not yield a definitive result for the case under consideration.
Comparison between mean field theories for a Heisenberg spin-Peierls transition
Authors: Lépine Y.
Published: April 2011

Three different approaches used to describe the Heisenberg spin-Peierls transition for a one-dimensional chain are compared. First the Hartree–Fock approximation of Pytte, which is a special case of the Soos approach, gives the simplest mathematical expressions and a Ginzburg–Landau expansion for the free energy. However, the numerical results obtained are less accurate than other theories, when compared with the exact asymptotic values. The most accurate numerical values are given by the theory of Soos. Unfortunately the appearance of an antiferromagnetic order at low temperature and at low distortion makes it qualitatively incorrect in this range of parameters. The approach of Beni produces numerical values intermediate between the other two. It is thus, in our opinion, the best compromise although a small first order transition is predicted, in opposition to the two other cases. Comparison of the Beni results with those experimentally obtained for TTF-CuBDT gives a lower spin–phonon coupling constant than that predicted from the Pytte theory. Also a better agreement with experiment for the magnetic field dependence of the lowering of the critical temperature is obtained.
Lower bounds for the ground states of the He-isoelectronic series
Authors: Fraga Serafin
Published: April 2011

A formulation, based on the concept of null local kinetic energy regions, has been developed for the determination of lower bounds for the ground state of a two-electron atom. Numerical results, obtained from Hartree–Fock functions, are presented for the elements He through Kr of the two-electron series.
Sputtered thin film electrodes for photoelectrochemical cells
Authors: Soliman A. A. , Seguin H. J. J.
Published: April 2011

Semiconducting TiO2 film photoelectrodes were prepared by dc sputtering from a simple hot pressed TiO2 powder target. To make the target semiconducting, it was first heated in a hydrogen atmosphere. Films so produced on heated glass substrates were polycrystalline and strongly adhered to the substrates. When tested for photoelectrolysis, these films were chemically stable and did not exhibit any photodecomposition. The spectral response was investigated and a main absorption edge at ~400 nm was obtained. The technique appears attractive for inexpensive large scale production of photoelectrodes for solar-hydrogen conversion.
Structures of conserved currents and mass spectra for scalar fields. III. Current classification scheme in terms of Killing equations and the Goldstone theorem
Authors: Shintani Meiun
Published: April 2011

We present a new classification scheme for the currents Jμ(x) = Qμν(x)Cν(x) in terms of the solutions of the Killing equations for Cμ(x). The new scheme enables us to treat any coordinate transformations (e.g., special conformal transformations), and to discuss the mass spectra for the scalar particles in a conformally-invariant system. Moreover, with the aid of the generalized Goldstone theorem exploited in the previous article under the same title, we shall point out the nonexistence of the Goldstone boson with regard to the special conformal transformations.
SU(n) gauge theories at finite temperature. A "Z(n) bubble" analysis
Authors: Weiss Nathan
Published: April 2011

SU(n) gauge theories at finite temperature are examined in terms of the spontaneous breaking of a Z(n) symmetry. It is suggested that the phase transition at finite temperature results from the formation of "bubbles" of an alternate Z(n) vacuum. These Z(n) bubbles are analyzed for lattice gauge theories in the dilute gas approximation and the results are compared with the Monte-Carlo calculations of McLerran and Svetitsky.
The magnetic properties of the oxygen–hole aluminum centers in crystalline SiO2. II. [AlO4/H+]+ and [AlO4/Li+]+
Authors: Nuttall R. H. D. , Weil J. A.
Published: April 2011

The centers [AlO4/M+]+, formed in α-quartz by X-irradiation at 77 K, contain an aluminum ion substituted for a silicon ion, with an electron removed from a neighboring oxygen by the ionizing radiation. In addition, there is an interstitial ion M+ which acted as a charge compensator before the irradiation. Centers [AlO4/H+]+ and [AlO4/Li+]+ have been re-examined by EPR (at ca. 35 K), including measurement of small hyperfine splittings due to the compensator ions. The spin-Hamiltonian parameter matrices (i.e., [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text]) show that the hole-trapping oxygen in these species is linked via a "short" bond to aluminum (there are two different Si–O bond lengths in quartz). The probable positions of the compensating ions (Li+, H+) in a channel parallel to the crystallographic c-axis are reported.
Equations of motion in a generalized theory of gravitation
Authors: Mann R. B. , Moffat J. W.
Published: April 2011

The problem of the motion of test particles is studied in a theory of gravitation based on a nonsymmetric gμν. According to the conservation laws the test particles can follow two kinds of geodesies, depending on the definition of a local inertial frame in the theory. One of these geodesies is nonmaximal and leads to a timelike and null world line complete space when a new parameter l, that occurs as a constant of integration in the spherically symmetric, static solution of the field equations, satisfies [Formula: see text]. In the theory, the parameter [Formula: see text] where N is the number of fermions in a system and a is a new universal coupling constant that satisfies [Formula: see text]. The physical implications of l and the associated conservation law of fermion number is discussed in detail.
Equivalence principle for charged bodies in a theory of gravitation
Authors: Mann R. B. , Moffat J. W.
Published: April 2011

The motion of a test body made of electromagnetically interacting point particles, falling in the static spherically symmetric field of the Hermitian theory of gravitation is shown to not disagree with the Eötvös–Dicke–Braginsky experiments for the equivalence principle. The modified Maxwell equations are calculated in the isotropic static spherically symmetric metric, and the role of the equivalence principle in the new theory is discussed in detail.
Canadian high energy electron ring (CHEER): Exploring the microcosm at 10−18 m
Authors: Isgur Nathan
Published: April 2011

A large group of Canadian physicists has been studying the feasibility of building an electron storage ring (CHEER) tangent to a proton accelerator to study electron–quark collisions at extremely high energies. This article provides an overview of the physics, machine, and detector developments of the CHEER project along with a brief summary of the status of the project.
Kinematics of electron–proton collisions
Authors: Campbell B. , Elias V. , Frisken W. R.
Published: April 2011

Kinematics of electron–proton collisions are presented for massless and massive parton constituents and outgoing leptons.
Antenna patterns in electron–proton scattering
Authors: Migneron Roger , McKeon Gerry
Published: April 2011

Using the calculations of Peccei and Rückl, numerical results are generated to describe the angular energy distribution in electron–proton scattering. When one-gluon emission is taken into account, an azimuthal asymmetry is observed in the energy distribution about the axis defined by the virtual photon and the incoming hadron.
New currents at CHEER
Authors: Krauss L. M. , Lee H. C. , McPherson A. C. , Watson P. J. S.
Published: April 2011

Various variants on the standard Weinberg–Salam model are analysed in terms of current limits and possible rates at CHEER.
Model for production and decay of a heavy lepton via electron plus photon mode
Authors: Resnick L.
Published: April 2011

A variant of the standard SU(2) × U(1) model is considered for the vertex e1e2γ, where e1 is the electron, e2 a heavy [Formula: see text] lepton, and γ the photon. The model mixes e1 and e2 via a scalar (weak isodoublet) field [Formula: see text] which has a mass scale [Formula: see text]. This is in addition to the usual Higgs field. The decay width for e2 → e1 + γ is calculated. The production cross section in the forward direction for e1 + p → e2 + p via one photon exchange is calculated, where p is the proton. Numerical estimates are made for some cases of experimental interest.
Electroproduction as a test of confinement
Authors: Elias V.
Published: April 2011

Salient features of the integer quark charge model of Pati and Salam are discussed. Significant departures from conventional electroproduction phenomenology are shown to occur below the energy threshold for the production of colored hadrons. The calculation of electroproduction structure functions below and above this threshold is presented in detail, and phenomenological consequences for deep inelastic scattering are discussed.
On the quenching of the spin flip excitation strength due to the isobar–hole excitation process
Authors: Kohno M. , Sprung D. W. L.
Published: April 2011

The effect of the isobar-hole excitation process on the [Formula: see text] transition strength is calculated in first order perturbation theory for finite nuclei (12C, 48C, 90Zr, and 208Pb), using Hartree–Fock wave functions. The pion and ρ-meson exchanges are taken into account for the NN–NΔ transition potential using a realistic two-body correlation function. The results show a considerable reduction effect (about 30%) and favourable A-dependence.
The Salter vapor pressure equation revisited: a new estimate of the anharmonic effects in rare gas solids
Authors: Aziz R. A. , Chen H. H.
Published: April 2011

The Salter equation for the vapor pressure of a monatomic crystal was applied to the data of Chen et al. The relative magnitudes of the terms were re-examined and the importance of the Debye and anharmonic terms were noted. New values of the anharmonic coefficients were determined by adjusting these until the derived values of the static lattice energy matched ones calculated on the basis of recent potentials.
Pure vibrational Raman spectra of simple molecular crystals: Ar–N2, Ar–O2, Ar–CO, β–CO
Authors: Kiefte H. , Clouter M. J. , Rich N. H. , Ahmad S. F.
Published: April 2011

Interferometric techniques have been employed to study the polarized (pure) vibrational Raman spectra of N2, O2, and CO as dilute solutions in single crystal matrices of Ar. The observation of a clearly resolved and concentration dependent spectral structure is interpreted as arising from the clustering of solute molecules.
Two- and three-body effective electrostatic interactions in odd configurations of the iron group
Authors: Roth C.
Published: April 2011

Expressions for the two- and three-body effective interactions in the configurations l″ and l″l′ were obtained, and then specialized for the case of the odd configurations in the iron group with l having a value of 2 and l′ a value of 1.There are four independent effective interaction parameters for the configuration d″. For the configuration d″p it was shown that there are 2 independent parameters for the two-body effective interactions, and 11 independent parameters for the three-body effective interactions.The results are being utilized in general investigtions for the odd configurations (3d + 4s)″4p in the iron group, and subsequently for the odd configurations in the palladium and platinum groups.
Hanle effect of the level of calcium and its density dependence
Authors: Mathur M. S. , Kelly F. M.
Published: April 2011

The Hanle width and hence the lifetime of the [Formula: see text] level of neutral calcium has been measured over a wide range of densities. The natural lifetime of the [Formula: see text] level is 20.07 ns. The depolarization cross section for collision with the ground level neutral atoms has been measured and [Formula: see text].
Dynamics of CO2 laser heated solenoids
Authors: McKen D. C. D. , Tighe W. , Fedosejevs R. , Offenberger A. A.
Published: April 2011

Experimental results are reported for long pulse CO2 laser production and heating of magnetically confined plasma columns. The plasma column is produced by an ionizing and heating wave propagation along the axis of a linear magnetic solenoid when laser radiation is focused into hydrogen gas contained inside the solenoid. The axial behavior is found to be reasonably well described by a "bleaching" wave model which predicts column length as a function of time. Radial behavior, following a transient ionization and expansion phase, is determined by a balance of ion thermal conduction and inverse bremsstrahlung laser heating. A finite ionization time is observed at the gas breakdown front. Energy balance measurements indicate that most of the incident laser energy is effectively coupled to ionization and heating of the plasma. Temperature measurements show good agreement with predictions of simple scaling models from which pressure balance gives a density value in agreement with experiment.
Electroproduction of low energy π+ from 3He
Authors: Sealock R. M. , Caplan H. S. , Zulkoskey B. W. , Szyjewicz A. , Tomusiak E. L.
Published: April 2011

Differential cross sections were measured for the electro-pion production from H and 3He at an incident energy of 200 MeV and pion energies from 7.3 to 12.1 MeV. Pion-angular distributions are presented and compared with theory. For hydrogen there is good agreement. A simple three-channel calculation performed for the pion production from 3He was found to overestimate the cross section at forward pion angles.
The electronic emission spectrum of triatomic hydrogen. IV. Visible bands near 5800 Å and infrared bands near 3950 cm−1
Authors: Herzberg G. , Hougen J. T. , Watson J. K. G.
Published: April 2011

In addition to the H3 and D3 bands previously analysed a strong and extensive band was observed near 5800 Å consisting of a large number of irregularly spaced sharp lines. This band can only be accounted for by transitions from the states derived from a 3d electron (2A1, 2E″, 2E′) to the 2p[Formula: see text] state which is also the lower state of the [Formula: see text] band at 6025 Å (paper I). The complexity of the spectrum arises from the interaction among the three component states brought about by uncoupling of the 3d electron from the symmetry axis, together with the perturbation of these states by the 3p[Formula: see text] state (the upper state of the diffuse [Formula: see text] band at 5600 Å). The 3d group of states emits also to the 3p2E′ state, giving rise to an infrared band at 3950 cm−1. The analysis of both the infrared and the visible band was carried out by means of an appropriate Hamiltonian written in terms of the rotational angular momentum R and the electronic orbital angular momentum L. On this basis the great majority of the lines have been assigned and sets of observed and calculated rotational levels have been evaluated. The agreement between observed and calculated levels, while good enough to leave no doubt in the electronic assignments, is not as good as might have been expected, most probably because of perturbations by vibrational levels of 3p2E′. These vibrational levels are not sufficiently well known and therefore cannot easily be included in the computation. Effective constants, for both H3 and D3, for the 3d group of states as well as the perturbing 3p[Formula: see text] state, have been evaluated. For several of these constants the ratio of the values for H3 and D3 deviates considerably from the theoretical ratio, suggesting a strong influence of additional perturbations.
Estimation of the nuclear temperature for the Cm(C,xn)No reaction
Authors: Pai H. L. , Andrews D. G.
Published: April 2011

In using the Jackson model for the calculation of the excitation function for the multi-neutron evaporation reaction, the nuclear temperature is usually obtained by fitting to the experimental data. The present note introduces a method for the calculation of the temperature by using non-adjustable parameters and applies it to the Cm(C,xn)No reaction.
Rotational analysis of the 13 200 and 13 400 cm−1 bands of NO2 by means of Fourier transform spectroscopy
Authors: Perrin A. , Flaud J. -M. , Camy-Peyret C. , Luc P.
Published: April 2011

The analysis of two parallel absorption bands of NO2, at 13 400 and 13 200 cm−1 respectively, has been performed using high resolution Fourier transform spectra. This paper is an extension of the work performed on the 7390 Å band (13 500 cm−1) in 1977 by Hallin and Merer, and completed in 1980 by Perrin, Camy-Peyret, Flaud, and Luc.The lines involving the Ka = 0, 1, 2, 3, 4 stacks for the 13 400 cm−1 band and Ka = 0, 1, 3, 4 for the 13 200 cm−1 band have been assigned and considerable spin–orbit and/or Coriolis coupling induced transitions have been detected.The 13 400 cm−1 band can be considered as belonging to the [Formula: see text] electronic transition, while the 13 200 cm−1 band might be, as the 7390 Å band (at 13 500 cm−1), a transition within the ground state manifold which barrows its intensity through vibronic coupling from the 13 400 cm−1 band. Tentative vibrational assignments are given.
Measurement of the transport properties of liquid Rb using automated equipment
Authors: Cook J. G. , Meer M. P. van der , Brown D. J.
Published: April 2011

Equipment to perform low-level thermocouple thermometry using a computer, a digital voltmeter, and very low thermal offset switching has been used to measure the thermal conductivity, electrical resistivity, and thermoelectric power of Rb from its melting point, near 313 K, to 650 K. The data obtained, which are accurate to the percent level, may be explained by combining the effect of the elastic scattering of electrons by ionic density fluctuations, and the effect of electron–electron scattering.
Core polarization, relaxation, and relativistic effects in the first ionization potentials for some systems in Cu, Ag, and Au isoelectronic sequences
Authors: Migdalek J. , Baylis W. E.
Published: April 2011

Single-configuration relativistic Hartree – Fock values of the first ionization potentials for Cu through Kr7+, Ag through 16+, and Au through Pb3+ are computed in "frozen" and "relaxed core" approximations with and without allowance for core polarization. Effects of the polarization of the atomic core by the valence electron are included by introducing a polarization potential in the one-electron Hamiltonian of the valence electron. The core polarization potential depends on two parameters, the static dipole polarizability of the core α and the cut-off radius r0, which are chosen independently of the ionization potential data. It is demonstrated that by including the core polarization potential with a and r0 parameters which are simply chosen instead of being empirically fitted, it is still possible to account, on the average, for at least 70% of the discrepancy between the single-configuration relativistic Hartree – Fock ionization potentials and the experiment, a discrepancy usually ascribed to the contribution of valence-core electron correlations, and to bring the theoretical ionization potentials to an average agreement with experiment of around 1%. The core polarization contribution to ionization potentials is also compared with the contribution of the relaxation of the core and with relativistic effects. An estimate of 55.0 ± 0.1 eV is suggested as the best value of the ionization potential of Sb4+.
Order–disorder phase transition in FeAl alloys by neutron diffraction
Authors: Ahmed N. , Butt N. M. , Beg M. M. , Aslam J. , Khan Q. H. , Collins M. F.
Published: April 2011

The order–disorder phase transition in FeAl alloy for compositions 20.24, 24.15, 28.06. and 31.54 at.% Al has been studied by powder neutron diffraction. The phase transitions from α to FeAl and from FeAl to Fe3Al appear to be of a continuous nature. The value of the critical index β of the order parameter is found to be 0.302 ± 0.009.
Absolute N2O wavenumbers between 1118 and 1343 cm−1 by Fourier transform spectroscopy
Authors: Guelachvili G.
Published: April 2011

About 1500 N2O absolute wavenumbers measured in vacuum are provided. They cover a range of 225 cm−1, centered around 1250 cm−1. Their absolute accuracy extends from 50 to 125 × 10−6 cm−1 (1.5 to 4 MHz). The lines belong to 13 different absorption bands and to 4 different isotopic species, the rotational constants of which are given. Additional information on experimental intensity and halfwidth of the profiles can be used to appreciate the importance of each transition. These data, measured for the first time with a high information technique, are located in a spectral area where experimental wavenumber references were up to now practically absent. They should be useful for accurate calibration of diode laser and Fourier spectra.
Low frequency Raman spectra of the liquid and plastic crystal phases of O2, N2, CO, and of Ar crystals with these molecules as guests
Authors: Rich N. H. , Clouter M. J. , Kiefte H. , Ahmad S. F.
Published: April 2011

Low frequency Raman spectra of single crystals of orientationally disordered phases of oxygen, nitrogen, and carbon monoxide, and spectra of those substances as liquids show two linear segments in semi-log plots. Slopes of the higher frequency segments are nearly equal for all cases; slopes of the lower frequency segments are particular to the substance and are nearly the same in both liquid and crystal for O2 and CO. Spectra of single crystals of argon doped with O2, N2, or CO show two distinct features superimposed on a sloping background. Impurity molecule reorientation apparently accounts satisfactorily for all spectral features, but translation–rotation coupling may allow a contribution to the higher frequency feature arising from a local phonon mode in argon.
Molecular dynamics study of solid argon with N2, O2, and CO impurities
Authors: Nosé Shūichi , Klein Michael L.
Published: April 2011

Molecular dynamics calculations employing atom–atom (exp-6) potentials are reported for solid argon in which 5% of the lattice sites are occupied by diatomic molecules. At temperatures close to the melting point (T ~ 80 K) the molecules are reorienting rapidly with no preferred orientation. Upon cooling, however, a distinct preference is observed for the crystallographic [Formula: see text] direction. Power spectra that characterize the translational and reorientational motions in the system have been evaluated. The results are discussed in light of available experimental data.