bluuebunny/crossref_metadata_2025 huggingface dataset:
Adiabatic Perturbation Theory in Molecular Spectroscopy
Authors: Klselev A. A.
Published: April 2011

The Born–Oppenheimer method or adiabatic perturbation theory has long provided a formal basis for separation of the electronic and nuclear motions in molecules. According to it solutions of the molecular Schrödinger equation can be obtained using expansions in power series in the parameter κ = (m/M)1/4 where m is the electronic mass and M is the average mass of the nuclei; the zeroth-order term in the eigenfunction expansion was shown to be a product of the electronic, vibrational, rotational, and translational eigenfunctions. However, this zeroth-order separation of motions was established only qualitatively because the Hamiltonian expansion was not obtained in explicit form. Therefore the adiabatic perturbation theory (to be referred to as APT) appeared to be inconvenient in applications, and practical investigations in molecular spectroscopy were based on simplified models and approximations rather than on the APT. The present review attempts to clarify and remove difficulties impeding wider applications of the APT and to give examples of its practical use. For this purpose a molecule-fixed moving coordinate system (to be referred to as mcs) is introduced by means of the Eckart conditions, and the Hamiltonian is transformed to the electronic and nuclear coordinates defined with the help of the mcs. For the transformed Hamiltonian the Born–Oppenheimer expansion is written explicitly and order-by-order calculations of the APT are carried out up to the fourth-order equation for normal and linear molecules. The results are used to discuss the stability of normal molecules and the Renner effect in linear molecules. The stability is considered for the cases of degenerate and near degenerate electronic levels. Lowering of vibrational frequencies caused by the near degeneracy is also studied, and the results are applied to infrared spectra of hexafluorides. The Renner equations for the bending vibrations of linear molecules are derived from the second-order equation of the APT. The four-atomic Renner equations are solved approximately using expansions in power series in the Renner parameters; the results are applied to vibronic spectra of C2H2 and C2D2 molecules. The influence of the Renner effect on the rotational spectra of triatomic molecules is considered with the help of the sixth-order energy correction of the APT. Higher order APT calculations are discussed briefly in the last section.
Antiferromagnetic order in the Heusler alloy, Ni2Mn(MnxSn1−x)
Authors: Stager C. V. , Campbell C. C. M.
Published: April 2011

A series of Heusler alloys, with composition Ni2Mn(MnxSn1−x) has been studied. X-Ray and neutron diffraction techniques have been used to investigate the chemical order. Well-ordered alloys were prepared with compositions corresponding to x = 0.1. 0.2, 0.3, and 0.4. The magnetic properties of these ordered alloys indicate that the Mn atoms, which substitute for Sn atoms, are coupled antiferromagnetically to the ferromagnetic manganese sublattice.
The strong interaction shift in pionic 3He
Authors: Thomas A. W.
Published: April 2011

We calculate the multiple scattering contribution to the strong interaction shift in the π−3He atomic 1s level. The result is in reasonable agreement with recent measurements. However, it is also noticed that this particular system is very sensitive to the inclusion of absorptive effects. In fact, when the dispersive effect of absorption is included in the usual way, only one (relatively old) set of πN scattering lengths gives a result near the data. We stress the importance of a definitive measurement in both this system and the π−d system to clarify matters.
Mesure des intensités des bandes d'absorption rovibrationnelles 0 → 4 et 0 → 5 de l'acide iodhydrique gazeux
Authors: Niay P. , Bernage P. , Coquant C. , Houdart R.
Published: April 2011

By using a SISAM spectrometer with a 0.03 cm−1 resolving power we have measured the line-strengths for the 4 ← 0 and 5 ← 0 absorption bands of the HI molecule. The pressure in the White cell was important enough to assume the lines to be described through a Lorentz profile, and we have used the 'curve of growth' method. By using all the available data on the 1 ← 0,2 ← 0, and 3 ← 0 bands, we have calculated the first six coefficients of the dipole moment expansion series. The shape of the experimental dipole moment function shows that the HI bond is primarily covalent.
Intermolecular forces in hydrogen–noble gas mixtures
Authors: Rulis A. M. , Smith K. M. , Scoles G.
Published: April 2011

Improved crossed beams differential collision cross sections for H2–Ar and H2–Kr have been measured and new data obtained for H2–Xe with a new beam modulation technique. The data have been analyzed with simple potential energy functions. The resulting potentials are in quite good agreement with those obtained in other laboratories from the velocity dependence of the integral collision cross section and the analysis of the infrared spectra of the hydrogen–noble gas complexes. The predictions of several simple combination rules are also examined.
High-resolution emission spectra of MgH and MgD in the 600 to 850 nm wavelength region
Authors: Balfour Walter J. , Lindgren Bo
Published: April 2011

The emission spectra from a magnesium dc arc in hydrogen or deuterium have been photographed at high resolution from 600 to 850 nm. Thirteen new bands of MgH and 18 of MgD in the B′2Σ+–X2Σ+ system have been identified and complete rotational analyses have been performed. Term values have been obtained for all bound ground state rotational levels of MgH for ν = 4–9 and MgD for ν = 6–13 and limiting curves of dissociation have been used to determine the dissociation energy of MgH. The experimental value, D00″(MgH) = 1.27 ± 0.03 eV is in excellent agreement with theory. The ground state RKR potential curve and Franck–Condon factors for the B′–X system are reported. Data on the isotopic molecules 25MgH, 26MgH, 25MgD, and 26MgD have also been obtained.
Further high resolution studies of the system of formaldehyde
Authors: Birss F. W. , Ramsay D. A. , Till S. M.
Published: April 2011

Rotational analyses have been carried out for five bands of the [Formula: see text] system of formaldehyde. Molecular constants have been determined for the 21, 2142, 2144, and 44 levels of the excited state and for a level in Fermi resonance with 2144. Some local rotational perturbations are discussed.
Decay of 162,164,165Lu isotopes
Authors: Burman C. , Sen P. , Bakhru H.
Published: April 2011

The decay of the short lived 162,164,165Lu isotopes have been studied using high resolution Ge(Li) detectors in singles and coincidence. The Lu isotopes have been produced using an oxygen beam from the Heavy Ion Accelerator at Yale University via the reactions 151,153Eu(16O,Xn)162,164,165Lu. New gamma transitions belonging to the decay of 165Lu (12 min), 164Lu (3.1 min), and 162Lu (1.4 min) isotopes have been identified by following their half-lives. Based on the singles, coincidence, and half-life measurements, tentative level schemes for the 164,165Yb isotopes have been presented. Our results have been compared with the published data.
The Fröhlich Hamiltonian: mathematical results. III. Perturbation theory
Authors: Dormale Bernard M. de
Published: April 2011

We prove the validity of perturbation theory for the polaron model. After obtaining the usual results for the Hamiltonian without cut-off, we derive the effective mass and energy shift for the Hamiltonian with cut-off. We also introduce a simplified model whose exact eigenvalue and eigenvector can be computed.
Numerical analysis of short laser pulse superposition in a fluorescent dye medium
Authors: Faubert D. , Chin S. L. , Cormier M. , Boloten M.
Published: April 2011

We present a rate equation analysis of passive short laser pulse superposition in a fluorescent dye medium, where it is seen that a single dye solution may act as both an absorber and an amplifier. Amplification proceeds via stimulated emission following a population inversion created with the energy the dye gained through absorption. Numerical results are compared with published experimental data. The agreement between the two is qualitative.
Validity of the latest interpretation on primary energy estimation and dependence of on laboratory momentum
Authors: Bandyopadhyay B. K. , Betal B. K.
Published: April 2011

Interpretation on primary energy estimation by Bhowmik, Singh, and Kaul has been substantiated from the data obtained from interactions of a 70 GeV proton beam in nuclear emulsion. Criteria A and B have been applied for the classification of the cascade mechanism and tube mechanism for the energy estimation of individual events. From our experimental data it has been shown that the percentage of coherent production is not as high as claimed by this group, but energy estimation by this new method agrees fairly well with our incident proton energy of E = 70 GeV. Moreover, it is found that [Formula: see text] at 70 GeV/c and our data indicate that[Formula: see text] is independent of laboratory momentum beyond 20 GeV/c.
Etude numérique de la fonction de Green scalaire d'une cavité à l'aide d'une nouvelle équation intégrale
Authors: Imbeau Jacques A. , Darling Byron T.
Published: April 2011

We study numerically, with the aid of an IBM-370 computer, the Green's functions of a cavity afforded by the solutions of a new integral equation (B. T. Darling and J. A. Imbeau. Can. J. Phys. 56, 387 (1978)). A number of prolate spheroidal cavities whose eccentricities cover the complete range zero to one are employed, and the solutions are subject to the Dirichlet and von Neumann conditions at the surface. We use the Gauss–Legendre integration formula to replace the integral equation by a set of linear algebraic equations. The Green's function is evaluated by substituting the solution of this set in the formula of Helmholtz, using the same integration formula. Criteria for the optimization of this procedure also are developed and employed. The Green's function can be determined to high precision except in the immediate vicinity of the surface of the cavity where it suffers a well-known discontinuity. We also explore the use of the Helmholtz formula itself in the exterior region as an integral equation to obtain the Green's function of the cavity. We find that although the precision of the solution is much less than that afforded by the precedingly mentioned integral equation the precision is still within the range of practical application. All calculations used double precision arithmetic (16 significant digits on the IBM-370).
Phonon dispersion in Co0.92Fe0.08
Authors: Svensson E. C. , Powell B. M. , Woods A. D. B. , Teuchert W. -D.
Published: April 2011

The dispersion relation for phonons propagating along the [00ζ], [ζζ0], and [ζζζ] directions in face-centred-cubic Co0.92Fe0.08 at T = 296 K has been determined by means of neutron inelastic scattering. The results have been analysed to obtain atomic force constants, the frequency distribution function, and the temperature dependence of the Debye characteristic temperature and the mean square displacement of the atoms. On average, the frequencies for Co0.92Fe0.08 scale approximately as expected with those for Ni and Cu but there are definite wave-vector-dependent variations in the scaling which presumably reflect the different electronic structures of the three materials.
Cross sections for the 26Mg(p,n)26gAl(7.3 × 105 yr) and 26Mg(p,n)26mAl(6.35 s) reactions
Authors: King J. D. , Cheng C. W.
Published: April 2011

Cross sections for (p,n) reactions originating on 26Mg in its ground state and resulting in 26Al in either its 7.3 × 105 yr ground state or its 6.35 s 228 keV excited state have been calculated from a statistical compound nuclear model for the proton energy range from 4.8 to 7.0 MeV, which is of interest in nucleosynthesis due to explosive carbon burning in stars. The cross section for the 26Mg(p,n)26mAl(6.35 s) reaction has been measured over the proton energy range from 5 to 9.5 MeV and is found to be 2–4 times lower than the calculated cross section at overlapping energies. The calculated cross section for 26Mg(p,n)26gAl(7.3 × 105 yr) was found to be more than an order of magnitude greater than a measurement made previously at 6 MeV. These results suggest that cross sections calculated according to the statistical theory could introduce substantial error into any predictions involving the production of 26mAl or26gAl during a nucleosynthesis event.
Products of generalized equivalent operators in angular momentum theory
Authors: Luryi Serge
Published: April 2011

Generalized operator equivalents to the (bipolar) spherical harmonics [Formula: see text] are considered, viz. [Formula: see text], where the PJ are projection operators on the manifolds of definite angular momenta, A closed formula is derived for the coefficients of the Clebsch–Gordan decomposition of products of such operators.
The linear potential eigenenergy equation. I: the coefficients Kn(3l′)
Authors: Antippa Adel F. , Ky Toan Nguyen
Published: April 2011

We derive explicit expressions for the coefficients Kn(l) of the linear potential eigenenergy equation for values of the angular momentum quantum number given by l = 3l′. The coefficients Kn(3l′) are obtained by taking the asymptotic limit of the previously derived functions Kn3k+1(3l′), as k → ∞.
Features of a developing turbulent boundary layer measured in a bounded flow
Authors: Reichert J. K. , Azad R. S.
Published: April 2011

Experimental results are presented for turbulence intensities, correlations, skewness of u, ∂u/∂t. boundary layer growth, flatness factor of u, and intermittency for the bounded developing flow in the inlet region of a pipe (Re = 54 900). The results exhibit several unique features which are not observed for unbounded or flat plate turbulent boundary layers. A hypothetical physical mechanism accounting for the findings is offered which suggests that, for bounded flows, an exaggerated interaction occurs at the interface between the constrained core fluid and the surrounding, growing turbulent boundary layer. This hypothetical interaction mechanism could account for the nonasymptotic development of bounded flows and it is suggested that a more detailed study using interface conditioned sampling measurements is warranted.
Generalized mean field theory of molecular liquids. II. Thermodynamic properties
Authors: Gray C. G. , Henderson R. L.
Published: April 2011

The generalized mean field (GMF) theory for the angular pair correlation function g(rω1ω2) for a molecular fluid, derived in an earlier paper, is applied to the calculation of the fluid thermodynamic properties. Explicit expressions are derived for the contribution of the anisotropic intermolecular forces to the free energy, energy, and pressure of the fluid. Numerical results are presented for a fluid with Lennard-Jones plus quadrupole–quadrupole interaction, and are compared to computer simulation and to perturbation theory (Padé) results.
On the theory of positron drift in a uniform electric field
Authors: Paul D. A. L. , Tsai J. -S.
Published: April 2011

The theory of electron drift and longitudinal diffusion in a uniform electric field is extended to positrons. The time- and position-dependent positron current is integrated to give a simple formula for the interpretation of positron drift experiments. The treatment is mathematically exact but neglects the transient attainment of a steady speed distribution of the positrons, and does not attempt to treat the boundary condition rigorously. These approximations are discussed, and justified under certain conditions.
Critical indices for spin correlation functions in ferromagnetic films
Authors: Gumbs G. , Griffin A.
Published: April 2011

Using the Ginzburg–Landau–Wilson (GLW) Hamiltonian, we obtain, with the mean-field approximation, explicit expressions for the spin–spin correlation function χ(z,z′) of a film of thickness L above the phase transition temperature Tc and the spontaneous magnetization [Formula: see text] below Tc. The boundaries are treated using a temperature-independent extrapolation length Λ. From our results, we verify explicitly that for finite L, the critical indices associated with the spin–spin correlation functions and the surface magnetization are identical with those for the analogous two-dimensional system, for both the ordinary (Λ > 0) and surface (Λ < 0) transitions. Our model results nicely exhibit the fact that as long as L is finite, when the temperature T approaches sufficiently close to Tc, there is a crossover from behaviour characteristic of a single surface to two-dimensional behaviour. Within the one-loop, Hartree self-consistent field approximation, we study the effects of mode–mode coupling on the surface layer susceptibility in films of varying thicknesses. The singular behaviour obtained in the mean-field approximation is found to be completely removed in systems of finite thickness, the susceptibilities only exhibiting a finite cusp at the transition.
The spin model. III. Analysis of high temperature series expansions of some thermodynamic quantities in two dimensions
Authors: Rogiers J. , Grundke E. W. , Betts D. D.
Published: April 2011

In this paper we report analyses of high temperature series expansions for the spin [Formula: see text] XY model on the triangular and square lattices. Quantities for which series are analyzed include the fluctuation in the transverse magnetization, fourth order fluctuations in the same quantity, second and fourth moments of the transverse spin–spin correlations, specific heat, and entropy. The evidence favours a phase transition at a finite temperature with conventional power law critical singularities. Scaling seems to hold but hyperscaling seems to be violated. Estimates for critical exponents include γ = 2.50 ± 0.3. Δ = 2.38 ± 0.2, and ν = 143 ± 0.10. The specific heat exhibits no singular behaviour at Tc.
Search for isomers in nuclei near N = 50
Authors: Taras P. , Haas B. , Merdinger J. C. , Styczen J.
Published: April 2011

Targets of 58,60,61,62,64Ni. Co, and Cu have been bombarded with 42 MeV 16O beams. Several isomers were produced but no new isomer was found, in particular in 74Kr which is expected to be a good candidate for yrast traps in the N = 50 region.
Dependence of fluorescence from laser irradiated SiF4 on the CO2 laser wavelength
Authors: Merchant V. E.
Published: April 2011

The energy per unit urea necessary for the occurrence of visible fluorescence from dissociation products of laser irradiated SiF4 has been measured for several values of CO2 laser wavelength and gas pressure. Fluorescence was observed at a lower irradiance when the laser was tuned far from the ν3 absorption band of SiF4 than when the laser was coincident with the absorption band. In the latter case the irradiance required for dissociation decreased as gas pressure was increased from 2 to 10 Torr. However, for nonresonant excitation the irradiance required increased with increasing pressure in the same pressure range. In addition the temporal response of the fluorescence to the exciting radiation was found to depend upon the laser wavelength.
Laser induced one-photon transitions between two short-lived negative ion states
Authors: Jung C. , Krüger H.
Published: April 2011

In the frame of a simple two-resonance model we study the general behavior of laser induced one-photon transitions between two electron scattering resonances (short-lived negative ion states) and relate these processes to resonance properties without the laser field. Our findings are illustrated by model calculations with square well potentials and are compared with the results of a recent experiment.
Local relative motion in general relativity
Authors: Cooperstock F. I. , Hobill D. W.
Published: April 2011

The distinction is drawn between problems in which single particle motion has physical significance and those in which relative motion between pairs of particles must be considered. Local relative motion is considered from the standpoint of the equation of geodesic deviation, expressed in arbitrary coordinates and in geodesic Fermi coordinates. A simple alternative approach to geodesic deviation using synchronous reference frames is described. Examples of relative motion in the Schwarzschild field and in a gravitational wave are discussed. Criticism of the efficacy of cryogenic cooling to enhance gravitational wave detector sensitivity is shown to be invalid. However, a cautionary note is expressed with regard to the necessity of a local observer to detect deviations from local planeness.
Binding energy of the Wannier exciton – ionized donor complex in the CdS crystal
Authors: Petelenz Piotr , Smith Jr. Vedene H.
Published: April 2011

The binding energy of the Wannier exciton – ionized donor complex in the CdS crystal is calculated for several sets of material constants proposed in the literature, with special emphasis on the correct low-temperature value of the dielectric constant. The electron–hole interaction is approximated alternatively by the potentials derived by Pollmann and Büttner, and by Aldrich and Bajaj. The best agreement with experimental values is found for the Aldrich–Bajaj potential, in accordance with previous results. The agreement is satisfactory even in the absolute values of the binding energies, and notably better than obtained previously.
Stability of an inhomogeneous fluid
Authors: Sobrino Luis De
Published: April 2011

The stability of the non-homogeneous possible equilibrium states of a fluid in a rigid container is studied in the context of the local thermodynamics approximation to mean field theory. General criteria for stability are derived. It is found that, in a certain precise sense, two-phase states are unstable against small perturbations if the interface does not intersect the walls. The effect of the walls and of the gravitational field in stabilizing a plane interface is studied in detail.
The exact fourth and fifth virial coefficients of an inverse-6 potential
Authors: Hall Donald S.
Published: April 2011

Numerical values are calculated for all of the four- and five-particle diagrams in the Mayer cluster expansion of the equation of state for an inverse-6 potential. These diagrams are then summed with the appropriate weightings to give accurate values for the fourth and fifth virial coefficients, which are found to be B4 = 0.02820(B2)3 and B5 = −0.0104(B2)4, where B2 is the second virial coefficient.
Disorientation of 42P1/2 potassium atoms, induced in resonant collisions
Authors: Skalinski P. , Krause L.
Published: April 2011

A (modified) Zeeman scanning method was used to determine the cross sections for disorientation of potassium atoms in the 42P1/2 resonance substate, induced in collisions with the ground-state atoms. Potassium vapor at densities of the order of 1011 cm−3 placed in a variable magnetic field was irradiated with σ+ polarized resonance radiation of wavelength 7699 Å emitted from a discharge lamp located in a constant field of 5.4 kG. The σ+ and σ− components of the resonance fluorescence emitted at right angles to the direction of excitation were monitored in relation to the vapor density as the variable field was scanned to make the σ+ resonance transition in the absorbing vapor coincide with the σ+ component present in the exciting light. As the vapor density increased, so did the admixture of the σ− component in the fluorescent light, which arises from collisional mixing between the mJ = 1/2 and mJ = −1/2 Zeeman substates. The resulting depolarization curve yielded the disorientation cross section σ1 = 4.0 × 10−11 cm2.
Structures of conserved currents and mass spectra for scalar fields. II. A covariant formulation of the generalization of the Goldstone theorem
Authors: Shintani Meiun
Published: April 2011

By adding the constraint equation [Formula: see text] on the generator G to our formulation exploited in the previous article under the same title (M. Shintani, Can. J. Phys. 58, 463 (1980)), we present a Lorentz-covariant approach to the generalized Goldstone theorem which applies even when the conserved current involves non-trivial c-number functions. As a result of the constraint equation, we derive a new key equation. By solving a new key equation together with the other key equations already obtained in the first part of this series, we can eliminate the massive mode and extract only the Goldstone modes. It is shown that any generator is either a relevant generator or an irrelevant one.
A study of the 3He(γ, π+)3H cross section near threshold
Authors: Dressler Edward T. , Tomusiak Edward L.
Published: April 2011

The effects of contributions from pion momentum, Fermi momentum, and Δ-resonance terms on the 3He(γ,π+)3H cross section near threshold are investigated in this paper. The pion momentum terms are shown to give important corrections individually, but their combined effect gives results which are almost equivalent to previous simpler calculations. Using a simple nuclear model, the results agree well with recent experimental data.
The use of a large-aperture radio system for meteor studies
Authors: Herring R. W. , Forsyth P. A.
Published: April 2011

A large sampled-aperture antenna array has been used to investigate the structure of the radio wave field scattered by meteor trails. The experiment measured the phase and amplitude of the radio waves in the frequency range 20 to 30 MHz at 58 points distributed over an aperture of almost 1.2 km. The temporal changes in the structure of the scattered radiation clearly show the influence of distortion of the meteor trails by atmospheric winds, but are incompatible with the widely accepted model which attributes fading and anomalous decay times to the distortion of a single trail. The observations seem to imply the simultaneous existence of two or more trails but whether these trails are due to fragmentation of the meteoroid in the atmosphere or to simultaneous entry of independent meteoroids is not clear.
The 170Er(t,p)172Er reaction at 15 MeV
Authors: Shahabuddin M. A. M. , Burke D. G.
Published: April 2011

Thirty-nine levels have been observed in the 172Er nucleus, for which virtually no nuclear structure information was previously available. The states at 0, 1332, 1470, and 2403 keV have distinctive L = 0 angular distributions and are therefore identified as Iπ = 0+ states. The 76 and 254 keV levels are interpreted as the 2+ and 4+ members, respectively, of the ground state rotational band. The ground state Q-value was measured to be 4.034 ± 0.004 MeV.
Yield of deep spallation products of medium to heavy mass targets bombarded with 480 MeV protons
Authors: Dautet H. , Bischoff G. , D'Auria J. M. , Pate B. D.
Published: April 2011

Absolute cross sections for short-lived alpha emitting, very neutron deficient nucleides resulting from the interaction of 480 MeV protons with several medium mass targets (Ho, Tm, Re, Ta, Au) have been measured at the TRIUMF facility (Vancouver, Canada). Activities were transported using a gas jet system and relative transport efficiencies for products of various Z were measured. Calculations for the production of such deep spallation products were performed using the empirical Silberberg–Tsao method and the more fundamental, intranuclear cascade – evaporation model, and compared against the observed values.
Anomalous absorption of Cr3+ electron spin resonance line intensities in guanidinium aluminum sulfate hexahydrate crystals
Authors: Manoogian A.
Published: April 2011

Experimental results are presented describing an anomalous absorption observed as a function of temperature for Cr3+ impurity ions in guanidinium aluminum sulfate hexahydrate (GAlSH) crystals. Measurements were made of the Cr3+ electron spin resonance line intensities, and a plot of the results upon cooling and warming the crystal shows the presence of an anomaly centered at a temperature of 280 K. The same effect was observed in measurements of the capacitance of undoped GAlSH crystals. The anomaly was found to be enhanced by the application of radio frequency power at 200 MHz to the crystal.
The extent of Pc 1 source region in high latitudes
Authors: Hayashi K. , Kokubun S. , Oguti T. , Tsuruda K. , Machida S. , Kitamura T. , Saka O. , Watanabe T.
Published: April 2011

The spacial extent of the source region of Pc 1 geomagnetic pulsations is investigated with respect to several such events recorded simultaneously at thirteen stations in Canada. The investigation is based on amplitude distribution obtained through reduction of the data acquired with induction magnetometers at those stations.Propagation from the source region is not isotropic but tends to align with geomagnetic latitude and longitude. The spacial gradient of amplitude near the source region becomes as large as 10 dB/100 km. Left-hand polarization does not seem to be confined to the source region. Size of source regions is discussed.
A comparison of the collision-induced light scattering by argon and by isotropic molecular gases
Authors: Shelton D. P. , Tabisz G. C.
Published: April 2011

The collision-induced two-body light scattering spectra of Ar, CH4, CF4, and SF6 in the gas phase at 295 K are discussed in terms of translational and rotational scattering mechanisms.
Analysis of the translational band measured in Ne–Ar mixtures with a new line-shape profile
Authors: Buontempo U. , Cunsolo S. , Dore P. , Maselli P.
Published: April 2011

The translational absorption spectra of Ne–Ar liquid mixtures, arising from the collision induced dipole moment, have been measured at different temperatures along the coexistence curve. The experimental line-shapes have been fitted with a new general profile suitable to reproduce the intercollisional interference effect. In this way we have derived the frequency ω0 that characterizes the rattling component of the motion of the impurity in the liquid. The self diffusion coefficient of Ne in Ar has also been derived from experimental values of ω0 using the Rice–Allnatt theory.
Fourth order intermolecular correlation functions from spectroscopic data and molecular dynamics calculations
Authors: Elsken J. van der , Heyes D. M.
Published: April 2011

The shape of collision induced absorption spectra of noble gas mixtures and the broadening of rotational lines of dipolar molecules dissolved in noble gas fluids are described in terms of time dependent perturbation theory up to fourth order. In combination with second and fourth order intermolecular correlation functions obtained from molecular dynamics calculations, conclusions are made about the importance of these functions for spectroscopic observations. The fourth order correlation functions are highly structured. The form taken by the connected part of the fourth order function depends markedly on the range of the probe interaction.
Post-Newtonian approximation of a new theory of gravity
Authors: Mann R. B. , Moffat J. W.
Published: April 2011

The post-Newtonian approximation is developed for a new theory of gravity based on a Hermitian metric gμν. The approximation gives Newtonian theory in lowest order, but differs from general relativity in post-Newtonian order. The equations of motion, energy–momentum conservation, and perihelion precession are investigated. The equations of motion are derivable from the conservation laws of the energy–momentum tensor. A multipole expansion of the metric is formulated, and the PPN parameters α, β, and γ are found all to be unity. Several new parameters occur, most notably I, which is related to the number density of fermions of a system.
Bound state energies and scattering phase shifts in a short-range potential
Authors: Banerjee S. N. , Chakraborty Pratima
Published: April 2011

The semi-classical Wentzel–Kramers–Brillouin (WKB) approximation has been used to determine the bound state energies and scattering phase-shifts in a short range potential having a cut-off. The corresponding pure coulomb cases are found to follow as limiting cases when the screening parameter tends to zero. The mutual interrelationship between the bound state poles and the analyticity of the scattering amplitude has also been explored in the context of the WKB approximation.
Dielectric relaxation studies. III. Allyl bromide and allyl ethers in liquid state
Authors: Jeyaraj M. , Sobhanadri J.
Published: April 2011

Complex dielectric permittivity measurements are reported at radio and microwave frequencies for four allyl compounds in the temperature range 30–70 °C. The analysis of dielectric data in terms of Cole–Cole arc, multiple relaxation times, and Higasi's distribution function reveals that the overall molecular rotation is the dominant relaxation mechanism in these unsaturated compounds. The activation parameters are evaluated assuming dielectric relaxation to be a rate process.
The magnetic properties of the oxygen–hole aluminum centers in crystalline SiO2. I. [AlO4]0
Authors: Nuttall R. H. D. , Weil J. A.
Published: April 2011

The most prominent paramagnetic impurity center in single crystal alpha-quartz X-irradiated at room temperature is [AlO4]0, which contains an aluminum ion substituted for a silicon ion, with an electron removed from a neighboring oxygen by the ionizing radiation. A reinvestigation of this species at ca. 35 K using electron paramagnetic resonance has disclosed weak multiplets due to hyperfine interaction of the unpaired electron with an 17O nucleus, present in natural abundance (0.037%). The spin-Hamiltonian [Formula: see text] parameter matrix [Formula: see text] describing this interaction confirms the above model of [AlO4]0 and yields the coefficients [Formula: see text] and [Formula: see text] for the oxygen s- and p-orbitals, respectively, in the unpaired electron wavefunction ψ. Similarly, weak multiplets caused by 29Si (4.70% natural abundance) have been analyzed. The eigenvectors of [Formula: see text], in conjunction with eigenvectors of other parameter matrices (i.e., [Formula: see text], [Formula: see text], [Formula: see text], [Formula: see text]), indicate that the trapping oxygen is one which would have a bond of the "long" type to the silicon replaced by aluminum (there are two different Si–O bond lengths in quartz). These eigenvectors also show that the axis of the oxygen p-orbital component of ψ is almost perpendicular to the Al–O–Si plane. The complete oxygen component of ψ has been used to obtain estimates of the dipolar contributions to [Formula: see text] and [Formula: see text], which however do not agree too well with the respective observed anisotropic components.
The nature of Λ0 production in annihilations at rest
Authors: Ghosh Dipak , Roy Jaya , Naha Sadhan
Published: April 2011

This paper presents a study of the nature of Λ0 production in antiproton–deuteron annihilation at rest. It has been observed that rescattering does not play a very significant part in Λ0 production and that a large portion of Λ0 is produced by three-body initial state interaction.
Subquark structure
Authors: Kalman C. S.
Published: April 2011

Six different models for subquark structure which have been proposed by many different people since 1975 are examined. Implications for experiments with the next generation of accelerators are described. How subquark structure fits into current ideas in quantum chromodynamics and the difficulties for any subquark model posed by the current values of the magnetic moments are also reviewed.
Radiofrequency system for CHEER
Authors: McKeown J.
Published: April 2011

The Institute of Particle Physics is preparing a proposal to design and build a 10 GeV electron–positron ring to study electron–proton collisions at the Fermi National Accelerator Laboratory using the 1000 GeV protons from the Tevatron. The design and operation of a high-power electron linear accelerator is very similar to the accelerating system in an electron–positron storage ring. This report describes the design of an rf system for the main ring which has many characteristics similar to that found in the Electron Test Accelerator at Chalk River. Discussion of quantum lifetime, the amplitude of synchrotron oscillations, and the consequent choice of the size of the beam aperture have led to the design of a new structure which operates at a higher frequency than that used in the large storage rings presently in operation.
Synchrotron radiation possibilities at CHEER
Authors: Mitchell J. B. A. , McGowan J. Wm. , Bancroft G. M.
Published: April 2011

The 10 GeV CHEER electron storage ring will produce more than 1 MW of synchrotron radiation per turn with photon energies extending from the far infrared to the hard X-ray region. The critical energy of the synchrotron radiation spectrum will be 22 keV.Applications of hard X-rays to materials analysis are described and a discussion of some of the problems which will be encountered in implementing a synchrotron radiation facility at CHEER is presented.
Multistable nonlinear Fabry–Perot interferometer
Authors: Chrostowski J. , Delisle C. , Vallee R. , Carrier D. , Boulay L.
Published: April 2011

The hybrid nonlinear Fabry–Pcrot interferometer is described in the multistable mode of operation. The multistable characteristics are obtained by using a multimode laser and properly adjusting the interferometer length. Self-oscillations in such a system are reported. A possible application in optical multivalued logical elements is outlined.
Temperature dependence of the resistivity of Hg3–δAsF6
Authors: Batalla E. , Datars W. R.
Published: April 2011

The resistivity of the linear-chain mercury compound Hg3–δAsF6 is reported in the temperature range 1.4–300 K. Electron scattering by one-dimensional and three-dimensional phonons on a cylindrical Fermi surface is used to calculate the temperature dependence of the resistivity which agrees with measurements of the resistivity between 4.2 and 90 K. The resistivity is determined by the Montgomery method which is extended to the case when electrical probes are not at the corners of a sample. The anisotropy ρc/ρa of the resistivity is in the range 95 ± 10 between 40 and 180 K. It is explained by a 1.4% undulation along the Fermi surface cylinders. Changes in the anisotropy give evidence of three-dimensional, long-range ordering at 120 K and short-range ordering of the mercury chains between 180 and 200 K reported previously. Hysteresis in the resistivity shows an unusual transition at 217 ± 3 K which is evident only upon cooling samples. There is no evidence of zero, c-axis resistivity below 4.1 K to support the suggestion that Hg3–δAsF6 is an anisotropic superconductor.
Uniaxial strain derivatives of the Fermi surface of copper
Authors: Ruesink D. W. , Perz J. M.
Published: April 2011

From a comprehensive experimental study of quantum oscillations in magnetostriction and torque, values have been deduced for all nonvanishing tetragonal and angular shear strain derivatives for the five principal extremal cross sections of the Fermi surface of copper, viz., the neck and belly normal to [111], the dogsbone normal to [110], and the rosette and belly normal to [001]. It is found that the neck is most sensitive to angular shear strain, whereas the bellies are most affected by uniform dilation. For the other orbits the magnitudes of shear and dilation derivatives are comparable.The results are self-consistent and agree with the experimental tensile stress results of Shoenberg and Watts. Earlier magnetostriction results for the neck obtained by Aron and by Slavin can be brought into agreement with the present data by recalculating the former using the now accepted value for the neck effective mass. The present experimental derivatives are in qualitative agreement with the theoretical values calculated by Lee, except for the tetragonal shear derivative of the [001] belly, for which the theoretical value is about 50% higher than the experimental one. This discrepancy is not fully understood.
Image processing in signal-dependent noise
Authors: Arsenault Henri H. , Denis M.
Published: April 2011

Techniques for processing of images in signal-independent additive noise are well developed. However, in practice the noise is often dependent on the signal. Some attempts to take into account the dependence of the noise on the signal have been made: our approach has been to generalize the homomorphic transformation, which is a point transformation that transforms the output of a system into a space where the noise becomes independent of the signal. Once this has been accomplished, standard techniques such as Wiener filtering should be applicable with results that are predictable. A rigorous proof of the general homomorphic transformation is given, and its accuracy is discussed. Applications to speckle noise and to film-grain noise are presented.
21S excitation of heliumlike ions
Authors: Singh C. S. , Srivastava R. , Rai D. K.
Published: April 2011

The variable charge, Coulomb-projected Born (VCCPB) approximation is applied to the calculation of cross sections for electron impact 11S–21S excitation in heliumlike ions (3 ≤ Z ≤ 8 and Si12+, Ca18+, and Fe24+). Differential and total cross sections have been reported for incident energies ranging from near threshold to five times threshold energy and are compared with other available theoretical estimates.
Measurements on the conductivity and diffusion of silver ions in Agx–NbSe2
Authors: Folinsbee J. T. , Jericho M. H.
Published: April 2011

Four probe ion conductivity as well as electrochemical time lag techniques have been applied to study the movement of silver in Agx–NbSe2. The results suggest that a dilute gas phase of silver coexists with a condensed phase in samples intercalated to [Formula: see text] and that a barrier to condensation exists for the silver in the gas phase. The high ion conductivity σi = 3.5 × 10−2 ?−1 cm−1 and diffusion constant D = 3.5 × 10−5 cm−2 s−1 for the gas phase suggests superionic behaviour of silver in NbSe2. Diffusion measurements give activation energies for silver of about 150 meV.
Electric field gradient in dilute transitional alloys of Cu and Al
Authors: Pal B. , Raj S. D. , Prakash S. , Singh J.
Published: April 2011

An attempt is made to explain the electric field gradient (EFG) and the asymmetry parameter η for Cu alloys with Ni, Pd, and Pt impurities and Al alloys with Sc, Ti, V, Cr, Mn, Fe, and Cu impurities. In Cu alloys, the valence effect contribution to the EFG is estimated using the Alfred and Van Ostenburg charge perturbation theory and the size effect contribution is adopted from that by Sagalyn and Alexander. Leading phase shifts are assumed to be η0 and η2 and these are determined by satisfying experimental data for residual resistivity and the Friedel sum rule. The effective charge on the impurity is estimated using the Friedel criterion of the bound state. It is found that the EFG increases with an increase in effective charge on the impurity. The size effect contribution dominates over the valence effect contribution. The agreement between the calculated and experimental values of the EFG and η for CuNi, CuPd, and CuPt is reasonably good. The calculations for the EFG and η for Al alloys are carried out following the charge perturbation theory due to Lautenschlager and Mrosan where the preasymptotic contribution is explicitly included through the energy dependence of phase shifts. Except for AlFe, the size effect contribution is greater than the valence effect contribution. The calculated and experimental values of the EFG and η are in reasonable agreement except for AlSc. Possible reasons for this are discussed.
Drift wave in the presence of a time varying inhomogeneous electric field
Authors: Misra K. D. , Pandey R. P. , Tiwari M. S.
Published: April 2011

The drift instability has been studied in the presence of an inhomogeneous time varying electric field directed perpendicular to the impressed magnetic field in the presence of a magnetic field, and density and temperature gradients, using nonlinear particle trajectories in the Maxwell–Boltzmann–Vlasov equations. The dispersion relation and growth rate have been evaluated for the drift wave propagating obliquely to the magnetic field in a plane normal to a density gradient. The stabilization/destabilization of the drift wave by the inhomogeneous applied electric field has been discussed. The application of these results has been suggested for space plasma.
The rotational a-type spectrum of [13C]diazirine, H2CN2
Authors: Möller Klaus , Vogt Jürgen , Winnewisser Manfred , Christiansen JØrn Johs.
Published: April 2011

The rotational spectrum of 13C isotopically enriched diazirine, H213C14N2, has been recorded in the region between 12 and 250 GHz. From an analysis of the nuclear hyperfine structure of the rotational transitions, quadrupole coupling and spin-rotational constants have been determined. Using Watson's A-reduced Hamiltonian, the rotational constants, the quartic and some sextic centrifugal distortion constants have been obtained for the ground vibrational state. The rotational constants obtained are[Formula: see text]The nuclear quadrupole coupling constants and the spin-rotation constants are[Formula: see text]for the two identical quadrupolc nitrogen nuclei. The accuracy of the constants obtained allows us to evaluate the line positions and hyperfine structure of any rotational transition in the microwave and millimetre wave region.
Vibration–rotation spectra of deuterated nitrous acid, DONO
Authors: Halonen L. O. , Deeley C. M. , Mills I. M. , Horneman V.-M.
Published: April 2011

High-resolution Fourier transform infrared spectra have been recorded and analyzed for the ν3, ν4, ν5, and ν6 fundamental bands of trans-DONO, and for the ν4 fundamental of cis-DONO. The spectral resolution was better than 0.01 cm−1, and the bands have been fitted using an asymmetric top Hamiltonian with a standard deviation of around 0.0006 cm−1.
The microwave spectrum of the chloromethyl radical, CH2Cl
Authors: Endo Yasuki , Saito Shuji , Hirota Eizi
Published: April 2011

The gas phase pure rotational spectrum of the chloromethyl radical, CH2Cl, has been observed for the first time in the millimetre wave region using a source frequency modulation microwave spectrometer equipped with a 1 m long free space absorption cell. The radical was generated by the reaction of CH3Cl with 2450-MHz microwave discharge products of CF4. The a-type R-branch transitions have been observed with resolved fine and hyperfine components for both the 35Cl and 37Cl isotopic species in the ground vibrational state. The small positive inertial defect. Δ0 = 0.0333 amu Å2, calculated from the rotational constants obtained for the 35Cl species indicates that the radical is planar in the ground vibronic state. The observed fine and hyperfine interaction constants are consistent with 2B1 symmetry, i.e., with the unpaired electron occupying a pπ orbital extending perpendicular to the molecular plane.
Multireference (single) and double-excitation – configuration interaction (MRD-CI) study of the radicals CN, SiN, and SiP, and the linear structures of HSiP and SiPH in their electronic ground and various excited states
Authors: Bruna Pablo J. , Dohmann Helmut , Peyerimhoff Sigrid D.
Published: April 2011

The relative stability of the three low-lying doublet states of the isovalent series CN, SiN, and SiP are calculated with highly correlated MRD-CI wavefunctions. The low-lying 4Σ+, 4Δ, 4Σ−, and 4Π states are analyzed and their equilibrium geometries and Tc values reported. The 4Π state of the radical CN is placed at an excitation energy that agrees with experimental inferences. In SiN, the theoretical treatment predicts a very small Tc value for A2Πi and finds no K2Σ state (earlier assumed), in accordance with recent experiments. The SiP radical contrasts with the other radicals because it possesses a X2Πi ground state and an energetically close-lying A2Σ+ state, in analogy with the experimental situation observed for the isovalent [Formula: see text] radical. The HSiP–SiPH species (linear geometry assumed) are reported for the first time. The energy difference is found to be practically zero in the present treatment. The dissociation energies and the vertical ionization potentials of the linear conformations also have been calculated. The theoretical dipole moments obtained for various electronic states of the AB radicals as well as for the ground states of the HSiP–SiPH components in Cxv symmetry are presented.