bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Energy Loss Spectra of NO2 and SO2
Authors: Bulger J. S. , Goodings J. M.
Published: April 2011

Electron energy loss data are presented for CO2, NO2, and SO2 at scattering angles of 0° and 60° and impact energies in the range 30–140 eV. Energy selectors of the 127° type have been used to detect energy losses in the range 0–20 eV. The energy loss data unify and supplement previous work involving a variety of techniques. They are discussed with reference to the Walsh correlation diagram, particularly with regard to the 6a1 molecular orbital with its unusually large variation of binding energy with bond angle. Below the ionization potential, the energy loss spectra are in good agreement with optical data and electron scavenging measurements at threshold; however, the Rydberg transitions have not reached their maximum relative intensities at the incident electron energies used. Excitation peaks corresponding to the ground state ion are observed in CO2 and SO2; for NO2[Formula: see text], a peak appearing at 9.7 eV is attributed to an excitation of the neutral molecule, however, since direct excitation of the ground state ion involves a large change in bond angle. Compared with CO2 and NO2, the SO2 molecule has an extra closed shell of 8 electrons such that the excitation of SO2+ appears to be dominated by autoionization at low incident electron energies. As the energy is increased to 138 eV, four peaks emerge which agree with previous photoelectron and Penning ionization data.
Atomic Charge State Ratios of 16O Ions from 18.7–59.7 MeV
Authors: Stocker H. , Berkowitz E. H.
Published: April 2011

Charge state fractions, 5+, 6+, 7+, and 8+, of high energy 16O ions between 18.7 and 59.7 MeV were measured and ratios of charge state fractions differing by one charge unit were found to follow an inverse fourth power dependence. The average ionic charge of a 16O beam varies from 6.4 to 7.6 over this range.
On the Vapor Pressure of Solid Argon
Authors: Chen H. H. , Aziz Ronald A. , Lim C. C.
Published: April 2011

The vapor pressure of solid argon was measured by a precision apparatus with a standard error of ±0.023 Torr in the temperature range from 75.0 to 83.8 K, and that of liquid argon to the same precision from 83.8 to 85.2 K. The data were used to determine the coefficients A and B of the two parameter vapor pressure equation, log10 p = A + (B/T), and to locate the triple point of argon by an extrapolation method. The results are in good agreement with those of other workers. The static lattice energy E0 of the solid and geometrical mean frequency ωg of the vibrational spectrum, corrected for the presence of lattice vacancies, gas imperfection, and finite crystal volume, were also determined from the data. When determined over successive small temperature intervals, E0 is found to increase as the temperature increases, as expected. The magnitude of E0 agrees with the value obtained from a lattice-sum calculation on the basis of a Lennard–Jones (6–12) potential to within ±0.17%.
Acoustic Phase Velocity Measurements along General Directions in Non-Isotropic Crystals. II. Layer Modes for Thin Films
Authors: McBride S. L. , Farnell G. W.
Published: April 2011

The usefulness of the immersion–reflection technique for the measurement of the angular dependence of the dispersion curves for elastic surface waves in anisotropic thin-film, substrate combinations is demonstrated. The example chosen consists of gold films on a substrate of Y-cut lithium niobate, the latter being both highly anisotropic and piezoelectric. The velocity accuracy of the measurements is about ±0.3% and the frequency of operation is limited by the attenuation in the liquid medium in which the test specimen is immersed.
Theory of Tunneling Assisted Electron Spin–Lattice Relaxation
Authors: Lee K. P. , Walsh D.
Published: April 2011

It is shown for an Eg orbital state and a tunneling splitting which is small compared with the Zeeman splitting that a strong Jahn–Teller coupling can lead to an enhancement of the direct spin–phonon coupling by several orders of magnitude. By comparing the theory with low temperature relaxation measurements on Cu2+ in a double nitrate the magnitude of several of the significant parameters associated with the Jahn–Teller problem is derived. A T2g orbital state strongly coupled to t2g modes of vibration can also have a strong spin–phonon coupling; the corresponding situation is briefly discussed.The strong coupling of the vibronic states to the lattice and the considerable range in the strength of this coupling have a number of practical applications.
Two Particle – One Hole Contributions to Magnetic Moments and M1 Transitions
Authors: Castel B. , Johnstone I. P.
Published: April 2011

The success of the core-particle nuclear model in predicting energy levels and E2 transitions is partially offset by strong disagreements on M1 rates. A perturbation method suggested recently by Green is used to determine the contributions to magnetic moments and M1 transitions from 2p-1h components. A marked improvement on previous M1 results is obtained with realistic values of spectroscopic parameters.
Is Unitarity a Must for the Existence of the Sum Rules for KL–KS Decay?
Authors: Gien T. T.
Published: April 2011

It is pointed out that the sum rules for KL–KS decay still can be derived even if the S matrix is only asked to satisfy a weaker condition than unitarity. Consequently, such sum rules still exist for a physical process with an absorption effect present.
Nature of Some Transitions Occurring in 97Nb Populated from the Decay of 97Zr
Authors: Murty D. S. , Jagam P. , Lakshminarayana V.
Published: April 2011

Some of the low energy gamma transitions occurring in the decay of 97Zr to 97Nb were investigated with a 50 cm radius double focusing magnetic spectrometer. On the basis of the conversion coefficients determined from this investigation, a gamma–gamma directional correlation experiment was carried out for the 355–1750 keV cascade occurring in 97Nb. The combined results of the two investigations made it possible to assign spins and parities for a few levels in 97Nb for the first time.
Breakdown and Sustaining Mechanism in Amorphous Semiconducting Threshold Switches
Authors: Armitage D. , Brodie D. E. , Eastman P. C.
Published: April 2011

The breakdown and sustaining mechanism in Te48As30Si12Ge10 alloy glass switching, using a planar electrode structure, has been investigated with the aid of a scanning electron microscope. This geometry permits direct observation of the conducting filament in the 1 μ gap samples studied. The switching and sustaining mechanism involves high temperatures in the filament, well beyond the melting temperature of the glass. A simple model is suggested for the switching which will allow sufficient energy to enter the filament and melt the glass, switching it to a high conductivity state in the subnanosecond times observed. It is suggested that avalanche breakdown initiates the predominantly thermal process.
Photometric Analysis of Spectrograms of Two Perseid Meteors
Authors: Cook A. F. , Halliday I. , Millman P. M.
Published: April 2011

Calibrated photometry has been carried out on two Perseid meteor spectra photographed near Ottawa in 1957. The peak brightness of these meteors in the flares reached at least −11 absolute photographic magnitude. Some 80 atomic and molecular features were identified in the two spectra, which corresponded with the normal spectral type for bright Perseids. Absolute fluxes for the radiations from atomic lines, molecular nitrogen bands, and meteor train features have been listed.
Autoionized Series in the Arc Spectrum of Arsenic
Authors: Bhatia K. S. , Jones W. E.
Published: April 2011

The absorption spectrum of arsenic vapor produced by the flash discharge of AsF3 vapor has been photographed in the vacuum ultraviolet region down to 1216 Å by means of a 10 m vacuum spectrograph. Four new series corresponding to three limits of 4s24p2(3P)ns have been extended to include [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text]. The ionization potential for As I is revised and the values for the second and third limits are calculated from the new series. Autoionization of the series above the first limit and many examples of perturbations are outlined. Measured wavelength and relative intensities for 198 new lines are added to the previous analysis.
Helical TEA-CO2 Lasers
Authors: Fortin R. , Gravel M. , Tremblay R.
Published: April 2011

A transversely excited atmospheric TEA–CO2 laser having a helical electrode configuration is described and analyzed. This laser configuration possesses a radial gain profile which naturally favors the excitation of the lowest-order mode of the resonator. Pulses of 0.7 J, having a peak power close to 1 MW, have been obtained in the fundamental mode. However, a strong diverging lens effect caused by the transverse electric discharges in the laser cavity produces a far field beam divergence twice as small as that calculated from the geometry of the resonator. This lens effect has also been used to lase with some geometrically unstable cavities. Two independent types of measurements, performed to study this lens effect, are shown to agree with a proposed theoretical model.
Enhanced Low-Energy E2 Transitions in the Odd-A Isotopes of Sb, I, Cs, and Pr
Authors: Goldstein I. V. , Pinho A. G. de
Published: April 2011

The intermediate coupling version of the unified model was used to calculate E2 transition rates in some odd-mass isotopes of Sb, I, Cs, and Pr. The observed enhancement of these transitions is reproduced and regular variations of the transition probabilities in groups of neighboring isotopes are explained.
Nucleon and Deuteron Reduced Widths of the Positive Parity (T = 1/2) States of the Mass-5 System
Authors: Ramavataram S. , Ramavataram K.
Published: April 2011

Reduced widths for nucleon and deuteron emission from the positive parity (T = 1/2) states in the region of 16 to 20 MeV excitation in the mass-5 system have been calculated using the R-matrix theory. Shell model wave functions were employed to describe the relevant states. Excellent agreement is obtained with various aspects of the experimental results on the well-established 3/2+ resonance at 16.6 MeV. Values for the proton and deuteron partial widths and the γd2/γp2 ratio for the 1/2+ resonance at 18 MeV and 5/2+ resonance at 20 MeV are presented. The calculated proton partial width for the 5/2+ resonance is in the range of values estimated from recent analysis of the p–4He phase-shift data.
de Haas–van Alphen Effect and Localized Spin Fluctuations in Dilute Al–Mn Alloys
Authors: Paton B. E.
Published: April 2011

The de Haas–van Alphen effect in dilute alloys of aluminum-manganese has been measured using the field modulation technique at magnetic fields up to 60 kG and temperatures between 1.1 and 4.2 °K. The period, effective mass ratio, and collision parameter of the third zone y orbits were found to increase linearly on alloying. The increase in the collision parameter attributed to the resonant d scattering by the localized states on the impurity atoms was found to be approximately 10 times larger than the increase observed in aluminum alloys with nontransition element impurities. The effective mass ratio was shown to be enhanced by the electron–phonon interaction and by the localized spin fluctuations on the impurity sites. The parameters which describe the localized state were calculated from the experimental results in the framework of a renormalized theory of localized spin fluctuations and were found to be in agreement with similar parameters calculated from other physical properties. The de Haas–van Alphen results are consistent with the conclusion that the localized state of manganese impurities in aluminum are nonmagnetic but strongly enhanced by localized spin fluctuations.
Nuclear Photo-Emission Following Radiative Pion Absorption
Authors: Guy Reed , Eisenberg J. M.
Published: April 2011

We consider the process in which the radiative absorption of a bound pion is followed by photon de-excitation of the residual nucleus. The particle–hole formalism is used for the evaluation of nuclear matrix elements and it is assumed that odd-parity spin–isospin nuclear states are excited by the radiative pion absorption mechanism. Results are presented for 12C and 16O, including energy distributions for the outgoing photons for the case in which the pion is absorbed from the 2P atomic orbital.
The 14ND – 15NH Mass Difference
Authors: Kerr Donald P. , Bainbridge Kenneth T.
Published: April 2011

The 14ND – 15NH mass difference was measured directly using three different mass doublets. The result is compared with other values obtained from mass spectrometric data and nuclear reaction data.
Transport in some Alkalis
Authors: Hayman B. , Carbotte J. P.
Published: April 2011

We have calculated the constant pressure and constant volume ideal electrical resistivities of the alkali metals Na, K, and Rb. In addition we have also calculated the ideal thermal resistivities of K and Rb. Information about the phonons is taken from a Born – von Kármán force constant analysis of dispersion curves at a particular temperature, obtained from inelastic neutron scattering. The shifts in phonon frequencies with volume are accounted for, approximately, by a uniform scaling using the known Grunëisen parameter and the measured volume changes. The electron–ion interaction is treated in pseudopotential theory and the one parameter Ashcroft form is used throughout. The calculations are reformulated in terms of two "transport frequency distributions", [Formula: see text] and [Formula: see text], which allow volume and temperature effects to be treated simply. The results compare very favorably with experiment over a wide temperature range.
An Interpretation of the Infrared Spectrum of Carbon Monoxide in a Solid Xenon Matrix
Authors: Lee K. O.
Published: April 2011

The infrared absorption band centered at 2133.1 cm−1 of carbon monoxide isolated in solid xenon at 20 °K has been interpreted as due to hindered rotation of the carbon monoxide molecule. The intermolecular interaction, comprising contributions mainly due to dispersion and repulsion, between carbon monoxide and the matrix produces an orientational effect. The rotational motion of the carbon monoxide molecule in the intermolecular field is treated quantum-mechanically so as to account for the main spectral features observed experimentally. From the calculations it is shown that a fraction of CO molecules in the matrix may undergo nearly free rotation to give a broad feature in the infrared band shape resembling the P- and R-branch envelope of the gaseous molecule in the wings. A large fraction of the CO molecules, those with energies less than the potential barrier height, execute librational motion, and thus are responsible for the intense Q branch at the band center.In a smaller matrix cavity, e.g., carbon monoxide in an argon or a krypton crystal, the "over-distortion" of the site would inhibit rotation altogether.
Electronic Spectrum of the N80Se Molecule in the Region 2840–3200 Å
Authors: Harding L. , Jones W. E. , Yee K. K. , Jenouvrier A. , Daumont D. , Pascat B. , Guenebaut H.
Published: April 2011

The vibrational and rotational analysis of 12 red degraded bands of N80Se, in the region 2800 to 3200 Å, is reported. These bands are attributed to two progressions, ν′ = 1 and ν′ = 2, of the subsystem C2Δ5/2–X2Π3/2 and to two progressions, ν′ = 0, of the system B2Σ–X2Π(a).Tables of molecular constants of the observed states are given. For the first time it has been possible to calculate the spin–orbit coupling constant, Aeff, of the ground state, X2Π(a).
Neutron–8Be Final-State Interaction in the Breakup of 9Be
Authors: Jeremie H.
Published: April 2011

The shape of a peak in the 9Be(p,p′)9Be* → 8Be + n reaction, as measured by Spencer et al., has been calculated according to final-state interaction theory using the effective-range approximation. The value of the neutron–8Be scattering length thus obtained is [Formula: see text] corresponding to a relative excitation energy of 14.5 ± 5 keV.
Spectromètres Electrostatiques. Partie II
Authors: Allard P. , Carette J.-D.
Published: April 2011

In this paper we present results of measurements done in order to verify the conclusions of a study concerning the cylindrical condenser used as an electrostatic electron spectrometer. The measurements are related to the angular electron distribution at the exit of the spectrometer, to the average value of the electron energy as a function of the exit angle, to the method of measuring the whole energy distribution of transmitted electrons, and finally to the linearity of the transmission characteristics of this spectrometer.
Sum Rule Photo-Disintegration Cross Sections for the Deuteron with Velocity-Dependent and Hard-Core Potentials
Authors: Raghavan S. S. , Srivastava B. K.
Published: April 2011

We apply the sum rules of Levinger and Bethe to calculate the integrated cross section[Formula: see text]and the bremsstrahlung-weighted cross section[Formula: see text]for the deuteron in the dipole approximation. In our calculations we use (i) Nestor's velocity-dependent potential and (ii) Reid's hard-core potential. Our results for σint and σb obtained with the velocity-dependent potential of Nestor and the hard-core potential of Reid agree well with experiments.
Effect of Oxygen on the Temperature Dependence of Electrical Properties of Reactively Sputtered Tantalum Films
Authors: Waterhouse Neil , Westwood William D.
Published: April 2011

The negative temperature coefficient of resistivity (TCR) displayed by β-Ta, which has thus far not been satisfactorily explained, has been examined by measuring the variation of electrical resistivity with temperature, from ~ 20–300 °K, and by measuring the Hall coefficients, at room temperature and at 77 °K, of films containing up to ~ 60 at.% oxygen. The Hall measurements indicate carrier concentrations of ~ 1022 cm−3 and mobilities of ~ 1 cm2/Vs. The analysis of the results has considered the granular structure of the films and has subsequently compared these results with an 'activated tunneling' model of conduction. Theoretical calculations which assume the film to be comprised of cubic grains separated by Ta2O5 agree well with the experimental measurements.Metallic conduction still appears to be contributing to the film properties even at the highest oxygen concentrations of the present investigation.
ENDOR of the 55Mn2+ Ion in MgO and CaO
Authors: Saxena G. P. , Vincent C.
Published: April 2011

Measurements have been made on the 55Mn2+ ion in cubic lattices of MgO and CaO at 4.2 °K and 9.43 GHz. Experimental ENDOR frequencies could be presented within 0.005% by the following spin Hamiltonian:[Formula: see text]The constants are as follows:[Formula: see text]
Investigation of the Rotary Lattice Mode in R2PtCl6 Compounds. II. From a Study of the 35Cl Nuclear Quadrupolar Spin–Lattice Relaxation
Authors: Armstrong Robin L. , Cooke Douglas F.
Published: April 2011

Measurements of the temperature and pressure variation of the 35Cl nuclear spin–lattice relaxation time in Rb2PtCl6 and Cs2PtCl6 are reported. The spin–lattice relaxation time is measured at atmospheric pressure for temperatures from 60 to 500 K and at four temperatures between 290 and 380 K for pressures to 5000 kg cm−2. Previously published data for K2PtCl6 are also included in the discussion. The Van Kranendonk theory of nuclear quadrupolar relaxation forms the basis of the analysis. The rotary lattice mode frequencies are deduced; they are of approximately the same magnitude and increase in the same sequence as the frequencies deduced from nuclear quadrupole resonance frequency measurements and from infrared and Raman data. An analysis of the pressure dependence of the spin–lattice relaxation time data yields order of magnitude pressure coefficients for the rotary mode frequencies. Finally, a thermodynamic analysis, which takes specific volume effects into account by incorporating both the temperature and pressure dependence of the data, is presented.
Excited States of Bound Excitons and Neutral Donors in CdS
Authors: Malm H. , Haering R. R.
Published: April 2011

A technique employing a monochromator to select the incident photon energy and a spectrometer to analyze the low temperature photoluminescence of CdS crystals has proven to be valuable, both in analyzing the usual photoluminescent spectra and in obtaining new information on excited states of bound excitons and excited states of neutral donors in the crystal. An accurate measurement of the donor energy levels and the donor binding energy gave a binding energy for the Cl donor in CdS of 33.0 ± 0.2 meV. Energies of excited states of the bound exciton complexes were also measured and for the bound exciton – neutral donor complex (I2 complex) some seven excited state levels were found. One type of radiative decay observed for this I2 complex is a radiative Auger process. This has important consequences in interpreting photoconductivity spectra.
Calculation of the Frequencies and Widths of Phonons in Cu0.97Au0.03
Authors: Bruno R. , Taylor D. W.
Published: April 2011

We have calculated the phonon frequencies and widths in the random alloy Cu0.97Au0.03, using low concentration defect theory and have compared our results with experimental observation. It was found essential to the description of the alloy system to include the effects of volume change on alloying. Morse potentials have been used to attempt to describe these effects as well as to estimate the force constant changes associated with the gold impurities.
Plane Wave Interaction with an Inhomogeneous Warm Plasma Column
Authors: Parbhakar Kanwal J. , Gregory Brian C.
Published: April 2011

The interaction of a plane electromagnetic wave with an inhomogeneous warm plasma column is studied as a boundary value problem using a wave matching method. The plasma is characterized by a uniform electron temperature T and a parabolic density distribution N00 (1 − αr2/α2), where N00 is the central line density, α the inhomogeneity parameter, and a the column radius. The coupled Maxwell's and first two moment equations, assuming scalar pressure, are solved numerically without the quasi-static assumption. The resonances cannot be characterized by a single parameter; the effects of α, T, and N00 are studied separately. The resonances are located by noting that the magnitude of the scattering coefficient is unity (for a unit amplitude incident wave) at resonance. The maxima in the scattering are associated with the maxima in the coupling.It is found that the dielectric or the main resonance is a reasonably good radiator, while the plasma wave resonances (Tonks–Dattner resonances) are rather poor radiators. A detailed analysis of the radial electric field inside the plasma indicates that the main resonance is essentially a cold plasma resonance. As for the resonant frequencies, our results are in good agreement with those of Parker, Nickel, and Gould.The radial electric field at resonance inside the plasma is very sensitive to electron temperature.For the main resonance the field distribution at low electron temperature approaches that of a uniform cold plasma at resonance.
Detection of the Plane of Polarization of 121 keV Linearly Polarized Photons
Authors: Logan B. A.
Published: April 2011

The polarization sensitivity of a 3 mm × 8 mm × 25 mm Si(Li) detector has been investigated with linearly polarized 121 keV photons. The results indicate that such detectors can serve a useful role in nuclear spectroscopy.
Helium Film Profile on a Gold and a Quartz Substrate
Authors: Hemming D.
Published: April 2011

The thickness of the static saturated helium film has been measured by an ellipsometric technique on a gold substrate at 2.13 °K and on a quartz substrate at 2.10 °K. The height, H, and the thickness of the film, d, are related by H = const. × d−n where n = 3.91 ± 0.15 and d = 323 ± 3 Å at H = 1 cm for the gold substrate. For the quartz substrate n = 3.08 ± 0.13 and d = 228 ± 2 Å at H = 1 cm; except that for thicknesses greater than 250 Å, the profile appears to steepen.
Rotational Line Strengths in 3Σ±–3Σ± Transitions with Intermediate Coupling
Authors: Tatum J. B. , Watson J. K. G.
Published: April 2011

Rotational line strengths (Hönl–London factors) are calculated for 3Σ±–3Σ± electric dipole transitions, allowing for nonzero values of the splitting constant λ. If the 3Σ states are intermediate between Hund's coupling cases (a) and (b) only one transition moment is required, whereas if there is a tendency to case (c) four transition moments may be required. The resulting formulas are compared with the observed spectra of the diatomic molecules of the Group VI elements. The same formulas are valid for 3Σ±–3Σ± magnetic dipole transitions.
Self-Diffusion in Gold
Authors: Morrison H. M. , Yuen Virginia L. S.
Published: April 2011

An electrolytic sectioning technique has been used to measure self-diffusion coefficients for gold in the temperature range 360 to 740 °C. At 740 °C our value agrees with previous work at this temperature, while the lower temperature values are larger than predicted by extrapolation of the well-established high-temperature behavior. The results are interpreted in terms of dislocation enhanced diffusion.
Memory Switching and Crystallization in Selenium
Authors: Armitage D. , Champness C. H.
Published: April 2011

A memory switching effect in bulk polycrystalline selenium has been investigated. I–V characteristics are related to structural changes revealed by microscopic examination, where it is shown that the switching mechanism is a crystal–amorphous phase transformation.A molten zone, produced by a direct current through the sample, undergoes a polarity dependent motion. The zone motion is discussed in terms of field-assisted ionic diffusion and it is suggested that this could be made into a useful crystal growing technique.
Influence of Spatially Dependent Electric Fields on Surface Wave Parameters in Mercury
Authors: Ionides G. N. , Curzon F. L.
Published: April 2011

This paper is an account of the influence of spatially nonuniform, time dependent electric fields on the amplitude, damping, and oscillation frequencies of surface waves on mercury. The results show that, by tailoring the geometry of the applied field, any single normal mode of desired geometry can be excited. Observations of the damping frequency are in very good agreement with a theory in which an immobile surface film is assumed on the mercury.
Reflection and Transmission of Electromagnetic Waves by Stratified Moving Media
Authors: Kong J. A.
Published: April 2011

The problem of reflection and transmission of electromagnetic waves by a stratified n-layer parallely moving medium has been solved. It includes the moving stratified medium and the nonuniformly moving medium with a stratified velocity profile as special cases. The results also reduce to all previous works with medium motion parallel to the boundary. Solutions are facilitated by the introduction of propagation matrices. Reflected and transmitted field intensities are calculated, and a detailed discussion on simple cases that have not been treated before is given to illustrate the general formalism.
Propagation of a Strong Circularly Polarized Electromagnetic Wave through Afterglow Plasmas near the Electron Cyclotron Frequency
Authors: Shkarofsky I. P.
Published: April 2011

We seek to explain the experimental observation of enhanced transmission of a strong right-hand circular wave near cyclotron resonance in an afterglow helium slab plasma occurring at earlier times than for a corresponding weak electromagnetic field. A strong field heats the electrons and alters the collision frequency and the velocity distribution function. For our experimental conditions, electron–electron relaxation processes can influence the distribution function. Furthermore, because of the field dependent absorption coefficient, the temperature and field strength can vary within the plasma slab. Although the collision frequency increase with temperature predicts an earlier time for stronger-field transmission at cyclotron resonance, none of the above processes is sufficient to explain the experimentally observed large spread in times of transmission for various electric field strengths. The explanation is ascribed to the fact that the electron density decay constant due to diffusion also increases with temperature, so that the electron density decay rates vary with electric field resulting in a larger spread in times of transmission. Experimental results from double probes, although operating under low sensitivity, suggest a decrease in density near the front edge of the plasma subject to strong fields.
Memory Effects in the Collision-Induced Spectra of Noble Gases in Liquid Argon
Authors: Buontempo U. , Cunsolo S. , Jacucci G.
Published: April 2011

We have measured the far infrared absorption spectra of dilute solutions of helium and neon in liquid argon arising from collision-induced electric dipole moments. The two spectra consist of broad bands similar in shape peaked at 70 cm−1 (Ne–A) and 120 cm−1 (He–A). They are characterized by a long high-frequency tail and a rapid fall at low frequency. The reduced line shapes are compared taking into account the difference in the duration of the collision-induced dipole moment. At high frequencies the two curves are similar to those observed in the gas phase. Their departure from the gaseous spectra at low frequencies is attributed to a negative correlation of the dipole moment induced in successive repulsive interactions.
39K 2.82 MeV Level
Authors: Robertson B. C.
Published: April 2011

Experimental M2 and E3 radiation widths for the 2.82 MeV level in 39K are obtained from available data and compared with theoretical predictions. It is shown that a large collective octupole admixture is not necessary to reproduce the E3 width and an inhibited M2 width is indicated, which is most likely due to the presence of 2 particle–3 hole components in the ground-state wave function.
Sequential Impact Mass Spectrometry: Estimates of Metastable Ion Cross Sections
Authors: Redhead P. A.
Published: April 2011

A trapped-ion source has been developed in which ions can undergo as many as 12 consecutive collisions with electrons; ions leaking out of the trap are analyzed with a mass spectrometer. When long-lived metastable states of the ions exist, the collision sequence may involve metastable states of the ions, e.g.[Formula: see text]where Xn represents an ion of charge multiplicity n, and Xn* represents a metastable ion. In a previous paper an approximate method was developed to estimate ionization cross sections for the case where the collision sequence involved only the ground states of the ions. The present paper extends this model to the case where metastable states are involved, and permits rough estimates of cross sections for excitation to and from the metastable states. The method is applied to experimental data for argon in the electron energy range of 40 to 100 eV.
Boson Method not Violating the Pauli Principle Applied to the Three-Quasiparticle System
Authors: Simard P. A. , Banville M.
Published: April 2011

The boson method is studied for a system with one and three quasiparticles. A basis is constructed in the ideal space in such a way that the Pauli principle is fully satisfied. The spurious states due to the particle nonconservation are properly eliminated. Numerical calculations are presented and a comparison is made with Kuo's method. The boson method can be easily extended to the study of systems having two phonons.
K-Shell Auto-Ionization in the Beta Decays of 151Sm, 169Er, and 210Bi
Authors: Campbell J. L. , McNelles L. A. , Law J.
Published: April 2011

The K-shell auto-ionization probability has been measured by Ge(Li) spectroscopy for three β− decays of low, medium, and high energy. The values obtained, (0.041 ± 0.006) × 10−4 for 151Sm, (1.0 ± 0.2) × 10−4 for 169Er, and (1.23 ± 0.1) × 10−4 for 210Bi, are discussed in terms of existing theories, and modifications to the latter are suggested.
Induced Fundamental Infrared Band of Nitrogen Dissolved in Solid Argon
Authors: Remigis J. De , Welsh H. L. , Bruno R. , Taylor D. W.
Published: April 2011

The induced fundamental infrared band of nitrogen dissolved in solid argon was studied over the temperature range 55–81 K with a path length of 40 cm and molar N2 concentrations of 1−2%. The spectrum consists of combination tones of lattice transitions with the N2 1 ← 0 vibrational transition. Lattice transition frequencies of 70 and 39 cm−1 at 55 K are identified with a local mode and vibrations of the host-lattice atoms respectively. We have computed the local-mode frequency over the experimental temperature range using one-defect theory in a harmonic approximation employing temperature-corrected experimental phonon frequencies and obtain good agreement with the observed values. The 39 cm−1 peak can be identified with features of the transverse region of the Ar phonon density of states.
Excitation of Electrostatic Fields in a Plasma by Transverse Electromagnetic Waves
Authors: Bachynski M. P. , Gibbs B. W.
Published: April 2011

An experiment has been conducted in which a plane transverse electromagnetic wave is incident from free space on a layer of isotropic plasma at small angles (0–12°) of incidence. Strong longitudinal electrostatic fields are observed within the plasma in the regions where the radian frequency of the incident wave equals the plasma frequency when the electric vector of the incident field is in the plane of incidence. Only weak longitudinal electrostatic fields are observed if the incident electric field is perpendicular to the plane of incidence. The observed phenomenon appears consistent with the field growth in a region where the dielectric coefficient of a plasma becomes zero.
Fermi Radii of Lithium by Positron Annihilation
Authors: Paciga J. J. , Williams D. Llewelyn
Published: April 2011

A collinear-point detector geometry has been used to study positron annihilation in single-crystal lithium. The results are interpreted in terms of the higher momentum components of the electron wave functions and the lithium Fermi surface. A consistent interpretation favors a value for the Fourier component V110 of the lattice potential of close to 0.10 Ry and a Fermi surface whose radius in the [110] direction is 2.9% greater than in the [100] direction. This latter result is consistent with Compton-scattering data and both results are in close agreement with the recent band-structure calculations of Rudge.
Collision-Induced Vibrational and Electronic Spectra of Gaseous Oxygen at Low Temperatures
Authors: McKellar A. R. W. , Rich Nathan H. , Welsh H. L.
Published: April 2011

The infrared fundamental band and the five strongest near-infrared and visible electronic bands of gaseous oxygen were studied from 90 to 115 K with path lengths up to 140 m in two low-temperature multiple-traversal absorption cells. The profile of the fundamental band is in good agreement with the theory of quadrupole-induced absorption except for a low-intensity residual in the Q-branch region. Although the electronic bands are less amenable to complete analysis, the general validity of a Boltzmann relation in their intensity distributions confirms their collision-induced nature. The temperature variation of the integrated band intensities is indicative of quadrupole induction for the fundamental and of overlap induction for the electronic bands; a somewhat too sharp rise at low temperatures may be due to the neglect of the quadrupole–quadrupole coupling in evaluating the pair distribution function.
Texture of Aluminum Wire
Authors: Banerjee Rajendra Lal , Banerjee Jharna
Published: April 2011

The texture of an extended aluminum wire has been studied by means of Debye–Scherrer photographs. In contrast to the predominantly [111] texture observed by the previous workers for the drawn and extruded aluminum wire, the extended wire exhibits only a [100] texture.
Shell-Model Calculations for 28Si
Authors: Behrman R. H.
Published: April 2011

A spherical-shell-model calculation is performed for 28Si where up to 3p–3h excitations in the 2s–1d major harmonic-oscillator shell have been included. A good account is given of the observed electromagnetic and β-decay data, although only fair agreement between the shell model and experimental spectra is obtained.
(e+, He) Total Scattering
Authors: Costello D. G. , Groce D. E. , Herring D. F. , McGowan J. Wm.
Published: April 2011

The total scattering cross section for e+ in He has been measured through two energy intervals, 1 to 4 eV and 17 to 26 eV. Through the lower elastic-scattering interval our results are consistent with the calculations of Drachman. From below the positronium formation threshold, at 17.8 eV to above the He ionization threshold, our results agree qualitatively with the calculations of Kraidy, who includes in his model virtual positronium and positronium polarization. Just below 17.8 eV the cross section is 0.35 ± 0.04 πa02. In these experiments a high-current linac has been used as a source of positrons and total beam attenuation has been used to determine the cross section.
Precise Atomic-Mass Differences in the Region
Authors: Barber R. C. , Bishop R. L. , Meredith J. O. , Southon F. C. G. , Williams P. , Duckworth H. E. , Rookhuyzen P. Van
Published: April 2011

A high-resolution mass spectrometer has been used to determine precise atomic-mass differences for 31 mass spectral doublets amongst the rare-earth chlorides. The precision of these determinations is in the range 0.6 μu to 3.8 μu, i.e. (2.5 to 25) × 10−9. The new data, when combined with previous data from this laboratory and with the known 37Cl–35Cl difference, provide mass-spectroscopically-derived connections between all naturally occurring odd-A nuclides from 141Pr to 169Tm and between all even-A nuclides from 142Nd to 170Er.
Excitation and Ionization of Hydrogen by Hydrogen-Atom Impact
Authors: Flannery M. R.
Published: April 2011

A semiquantal theory is applied to the examination of both the collisional excitation of the second and third excited levels of hydrogen and the collisional ionization from these levels, with the projectile hydrogen atom remaining in the ground state. Agreement with the Born cross sections is obtained.
Thermally Activated Glide in Normal and Superconducting Indium
Authors: Hutchison T. S. , McBride S. L.
Published: April 2011

Evidence is presented which shows that the flow-stress difference in normal and superconducting indium may be attributed to differences in thermal activation of glide dislocations.
A Capacitive Fourier Analyzer of Hydrodynamic Surface Waves
Authors: Curzon F. L. , Langille B. L.
Published: April 2011

A capacitive probe consisting of two plates ruled with vertical strips of varying width is described. It is shown that the device can be used to study the time dependence of individual Fourier components of surface waves on water. An account of tests on the selectivity and sensitivity of the probe is presented together with results indicating the utility of the probe under conditions which are normally adverse for other types of probe (i.e. the study of the growth of Rayleigh–Taylor instabilities on the surface of a fluid which is rapidly accelerated vertically.downward).
Shell-Model Lattice Dynamics of CsCl, CsBr, and Csl
Authors: Carabatos C. , Prevot B.
Published: April 2011

Detailed calculations are presented for the frequency distributions and dispersion curves of the three cesium-chloride-structure alkali halides: cesium chloride, cesium bromide, and cesium iodide. In the shell model applied to the study, the polarizabilities of both negative and positive ions have been taken into account as well as the simplified next nearest neighbor interactions. Theoretical predictions and experimental data are in agreement.
Surface Current Density on Perfectly Conducting Polygonal Cylinders
Authors: Hunter J. D.
Published: April 2011

A method is presented of obtaining numerically the surface current density on a perfectly conducting regular or irregular polygonal cylinder when the incident field is either electrically or magnetically polarized (TM or TE) in the axial direction. The surface current density is represented by a sum of continuous modal functions and satisfies the edge conditions. The extended boundary condition is satisfied and the uniqueness of the solution ensured by setting to zero each of the Fourier coefficients of the field around a circle inside the cylinder. Results are presented for a regular triangular cylinder symmetrically illuminated by plane and cylindrical waves.
Broadening and Shift of Atomic Lines Produced by Fast Electron Collisions
Authors: Bassalo J. M. , Cattani M.
Published: April 2011

In this paper general expressions for the width and shift of atomic lines produced by fast electron collisions are obtained. We use the recent quantum-mechanical theories developed to explain the pressure line shape in the impact approximation. Only isolated and Lorentzian lines are analyzed. The calculations are performed by expanding the scattering matrix up to the second Born approximation. The contributions of both elastic and inelastic virtual collisions are calculated. Degenerate and nondegenerate atomic states are considered.
A New Spectrum Probably Due to the Ion
Authors: Meinel H.
Published: April 2011

A new spectrum associated with diatomic carbon has been observed in absorption in a flash discharge at 2490 Å. This spectrum has been identified as a [Formula: see text] transition indicating that the absorber must be a C2 ion, either [Formula: see text] or[Formula: see text]. From a discussion of the experimental conditions, the molecular constants, and the electronic structure, it appears very likely that the carrier is [Formula: see text].
Mössbauer Effect Study of the Hyperfine Fields at the Tin Sites in Cu2MnSn, Ni2MnSn, and Pd2MnSn
Authors: Geldart D. J. W. , Campbell C. C. M. , Pothier P. J. , Leiper W.
Published: April 2011

The magnitude and sign of the hyperfine field at the tin site in the Heusler alloys Cu2MnSn, Ni2MnSn, and Pd2MnSn have been measured at 77 °K by means of the Mössbauer effect and found to be + 200 ± 10 kOe, + 87 ± 3 kOe, and −35 ± 2 kOe, respectively.Saturation hyperfine fields have been calculated using the virtual bound state model for a range of values of the parameters of the model. It is found that current theory is inadequate since it does not predict even the correct sign of the hyperfine field at tin sites in Cu2MnSn and Ni2MnSn.
The 5/2− Resonance at 850 keV in 15N(α,γ)19F
Authors: Rogers D. W. O. , Aitken J. H. , Litherland A. E.
Published: April 2011

A weak resonance at 850 keV in 15N(α,γ)19F corresponding to a level at 4681 ± 1 keV in 19F has been found. Angular distributions and Doppler shifts have been measured for the primary decays to the 5/2− level at 1.35 MeV (63%), 3/2− level at 1.46 MeV (31%), and the 5/2+ level at 197 keV (6%). A spin of 5/2 has been assigned to the resonance level and negative parity is shown to be very likely. The lifetime of the resonance was measured by the Doppler shift attenuation method to be τ = (15.4 ± 3.0) × 10−15 s or Γ = 42.8 ± 8.5 meV. The measured value of ωγ was 6.0 ± 1.0 meV. These measurements together with previous information on Γγ/Γ imply the observed M1 transition strengths are a factor of 20 weaker than predicted for the 5/2 member of the K = 3/2− band in 19F which has previously been associated with this level.
A New 1Δ–1ΔTransition of the TiO Molecule
Authors: Linton C.
Published: April 2011

The TiO spectrum has been excited by a microwave discharge through a mixture of helium, oxygen, and TiCl4 vapor. A rotational analysis of a strong band at 5240.5 Å has shown that it is the 0,0 band of a transition from a new 1Δ state to the a1Δ state of the TiO molecule. The origin of the band is at ν0 = (19 068.95 ± 0.03) cm−1 and the rotational constants of the new 1Δ state are[Formula: see text]
Studies of Ionospheric Inhomogeneities using Phase Interferometry of Satellite Beacon Transmissions at 136.410 MHz
Authors: Hajkowicz L. A.
Published: April 2011

A newly developed sensitive phase interferometer, based on a North–South and East–West antenna system, situated at London, Ontario, was used to record fast angle-of-arrival variations of the satellites ISIS-1 and ISIS-2 beacon transmissions at 136.410 MHz.The relative phase and corresponding amplitude scintillations indicate the presence of two distinct types of ionospheric irregularities which were classified as A-type and B-type. A-type predominantly occurred in a time interval centered on local midnight, and the major disturbance areas were south of the station. A number of them showed a near-field effect, which indicated the presence of F region field-aligned irregularities with large axial ratios.The B-type events, associated in publications with the sporadic E region, occurred at high elevation angles northwest and northeast of the station. Tentative results indicate that these events, predominantly recorded during daytime, are due to ionospheric irregularities occurring at altitudes considerably higher than those of the sporadic E region.
Analyse Rotationnelle de la Bande (0,0) du Système Orange de ScO
Authors: Stringat R. , Athénour C. , Féménias J. L.
Published: April 2011

The orange system of ScO has been reanalyzed as a 2Π → 2Σ transition. We have observed all the branches which are compatible with the selection rules ΔJ = 0, ± 1. We have not detected the hyperfine structure in the excited state, the coupling case being therefore aβ. The magnetic hyperfine interaction inducing the ground state doubling is the only one which appears; it has been analyzed by other authors who have shown that the coupling case for this state is of the type bβS.The use of an alloy hollow-cathode lamp, cooled with liquid nitrogen, has enabled us to improve the frequency measurements. The values of the constants have been obtained by a method by which, working directly with the Hamiltonian, the introduction of each parameter can be justified. The study of the Λ doubling in 2Π3/2 and 2Π1/2 levels leads us to values of ξ and η very close to those predicted for a pure precession case.
Positron–Vacancy Interaction in Aluminum
Authors: McKee B. T. A. , Jost A. G. D. , MacKenzie I. K.
Published: April 2011

Precision measurements of positron lifetimes in aluminum at 42 temperatures are presented. The data are analyzed in a manner consistent with both trapping and nontrapping models of positron–vacancy interaction. Both models can be characterized by two parameters, the vacancy formation energy and a trapping or enhancement parameter. The two-component trapping model seems to be favored by the data, but a one-component interpretation is possible. The values obtained for the vacancy formation energy in aluminum are 0.71 eV according to the trapping model and 0.78 eV according to the nontrapping model.
Flux Line Pinning by Large Normal Particles in Type-II Superconductors
Authors: Coote R. I. , Evetts J. E. , Campbell A. M.
Published: April 2011

The pinning of flux lines by large normal particles has been investigated as a function of field and temperature. The results are compared with a model for the magnetic pinning interaction at a phase boundary. The problem of the summation procedure for individual pinning interactions is discussed and it is concluded that the distortion of the flux line lattice caused by large normal particles is large enough for a simple direct summation to apply. This conclusion is supported by the experimental results. The experimental results also indicate that Anderson flux creep is not significant in this type of pinning system.