bluuebunny/crossref_metadata_2025 huggingface dataset:
Theoretical study of homogeneous perturbations. II. Least-squares fitting method to obtain "deperturbed" crossing Morse curves. Application to the perturbed 1Σu+ states of N2
Authors: Lefebvre-Brion H.
Published: April 2011

A method to obtain a "deperturbation" of perturbed vibrational levels is developed. The vibrational functions associated with two (or three) crossing Morse curves are used to set up an interaction matrix. The eigenvalues of this matrix are compared with the observed levels and the "deperturbed" Morse curves are obtained by a least-squares fitting. This method applied to the 1Σu+ states of N2 confirms the interpretation given by Dressler (following paper).
The lowest valence and Rydberg states in the dipole-allowed absorption spectrum of nitrogen. A survey of their interactions
Authors: Dressler Kurt
Published: April 2011

The ungerade singlet states of molecular nitrogen observed up to 115 000 cm−1 have traditionally been designated with some 20 letter symbols. It is shown that these levels do not belong to 20 different electronic states but that all of them can be ordered into six vibrational progressions of three valence states: b1Πu (j, b, d, m, p, q), b′ 1Σu+ (b′, g, g′, f, r), d′(1Σu− or 1Δu?), and of three Rydberg states: c1Πu (l, d″), c′ 1Σu+ (p′, r′, k, s′, h, h′), and o1Πu. The new assignments of observed levels to the states b, b′, c, and c′ are identical with those given by Carroll and Collins on the basis of new high-resolution studies of the absorption spectrum. It is shown here, that the irregularities of the vibrational intervals, rotational constants, isotope shifts, and intensity distributions within these progressions can be interpreted quantitatively on the basis of homogeneous interactions between valence and Rydberg states of the same species, especially between the pairs of states b1Πu + c1Πu and b′ 1Σu+ + c′ 1Σu+. Approximate quantitative deperturbations of the vibrational structures of these four electronic states are derived from a new set of deperturbation criteria, and the resultant potential curves, the electron configurations, and the observed predissociations are discussed. The deperturbation results for the b′ and c′ states are tested in more quantitative detail by Lefebvre-Brion in the adjoining paper.
High resolution absorption studies of the b1Πu ← X1Σg+ system of nitrogen
Authors: Carroll P. K. , Collins C. P.
Published: April 2011

New high resolution studies of the absorption spectrum of N2 have been made in the region 1015–795 Å. Analyses are given of 25 non-Rydberg bands of the type 1Πu–X1Σg+. It is shown that all of these bands, which include the i, j, b, l, m, p, and q groups of Worley, together with several new bands not previously observed, can be assigned to a single transition the upper state of which is called b1Πu. The pronounced irregularities in the vibrational and rotational structure of the b state are attributed to a homogeneous interaction with the first member (n = 3) of the ---(3σg) npπu, 1Πu Rydberg series. This perturbation is discussed in the accompanying paper by Dressier who recognized its importance in the interpretation of the spectrum. Diffuseness in the rotational lines of several bands at lower ν was observed and is attributed to predissociation by a triplet state, probably the C′ 3Πu state which goes to the 4S + 2D dissociation limit. Three levels of the b state show measurable Λ-type doubling which can be interpreted as caused by interaction with vibrational levels of the first member (n = 4) of the --(3σg) npσu, 1Σu+ Rydberg series. The assignment of 28 non-Rydberg 1Σu+ levels, including the b′, g, f, r, s, and t "states", to a single 1Σu+ state which is called b′, is also briefly discussed.
Recent observations of the auroral spectrum between 1.02 μ and 1.13 μ
Authors: Harrison A. W.
Published: April 2011

During the summer of 1968, observations were made of the auroral spectrum at 27 Å spectral resolution between 1.02 μ and 1.13 μ. Absolute brightnesses were estimated from the spectra for the N2+ Meinel (0–0) band, N2 1PG (0–0) band and 2D0–2P0 (N I) line after subtraction of the background night airglow spectrum and after correcting for atmospheric extinction. Simultaneous measurements of the N2+ 1NG (0–0) band and O I line at 5577 Å have facilitated the reduction of the infrared brightnesses to the equivalent international brightness coefficient III brightnesses.
Lifetimes and branching ratios of energy levels of 28Si. II
Authors: Alexander T. K. , Broude C. , Ferguson A. J. , Kuehner J. A. , LitherLand A. E. , Ollerhead R. W. , Smulders P. J. M.
Published: April 2011

The gamma rays from the 25Mg(α,nγ)28Si reaction have been studied for alpha-particle energies in the range 6.0 MeV to 7.2 MeV. A 25-cm3 Ge(Li) gamma-ray counter was used to observe the complex high energy gamma-ray spectra at angles between 0° and 130° to the alpha-particle beam. The lifetime ofthe7798-keV level was found to be 0.30 ± 0.10 ps by studying the Doppler broadening of the spectrum lines. The gamma-ray decays of the 8260, 8328, 8411, 8543, and 8587-keV levels were observed. The gamma-ray decays of the 8260 and 8543-keV levels had not been observed previously. The 8260-keV level decays to the first excited level at 1780-keV and the 8543-keV level decays only to the 4617-keV level. Information on the spin-parity combinations of these levels in 28Si was obtained by a measurement of the yield of alpha particles at zero degrees to the beam in the reaction 16O(16O,α)28Si.
Relative band intensities in the atmospheric and infrared atmospheric systems of molecular oxygen
Authors: Findlay F. D.
Published: April 2011

Relative band intensity measurements have been made for the (0,0) and (0,1) bands of the (a1Δg–X3Σg−) system of oxygen at 1.27 μ and 1.58 μ, respectively, and for the (0,0), (0,1), and (0,2) bands of the (b1Σg+–X3Σg−) system of oxygen at 7619, 8645, and 9970, respectively. The (0,2) band of the (1Σg+–3Σg−) system of oxygen has been observed for the first time. Emission was also observed from the (1,0) and (1,1) bands of this system. The observed relative band intensities are compared to those of earlier workers and to relative intensities calculated from theoretical Franck–Condon factors.
Isotope shift in the NMR of iron
Authors: Turrell B. G.
Published: April 2011

The zero-field NMR frequencies of two samples of iron with different isotopic constitution have been compared at various temperatures. An isotope shift is observed which is different from a previous estimate. A possible explanation for the isotope shift is suggested.
A moment theorem for resonance line shapes arising from decoupled Green's function equations
Authors: Frank Barry , Barrie R.
Published: April 2011

A theorem is derived which enables one to bypass quadrature in the calculation of moments of a resonance line obtained from any decoupling of the Green's function hierarchy of equations. These moments are those of the resonance line as expressed in terms of delta-function peaks prior to smearing. A comparison with exact theoretical moments then provides a test of the decoupling procedure as distinct from the smearing technique. The method is illustrated by application to the one-dimensional Ising model.
Spectroscopie atomique à l'aide d'un accélérateur Van de Graaff: Applications à l'hélium et à l'azote
Authors: Girardeau R. , Kerwin L. , Drouin R.
Published: April 2011

not available
Discrete water molecules in the vicinity of two oppositely charged ions
Authors: Ross Dieter K.
Published: April 2011

An attempt is made to describe the water molecules in contact with an ion pair in an aqueous solution. One possible arrangement consisting of 10 nonpolarizable water dipoles is considered and a comparison of various energy terms is made in order to decide what factors are most important. The two ions and their attached water dipoles are enclosed in a spheroidal cavity embedded in a dielectric continuum to represent the bulk of the water. It is shown that the energy associated with the water molecules lying in the central region between the two ions is practically unaffected by the cavity size. On the other hand, although the behavior of the "outer" water molecules is extremely sensitive to the cavity size it is a good approximation to the more precise statistical problem to place them in the position of minimum potential energy.
Electromagnetic diffraction by a circular aperture in a plane screen between different media
Authors: Thomas D. P.
Published: April 2011

The problem of diffraction of time harmonic, electromagnetic waves by a circular aperture in a perfectly conducting, plane screen between different media is considered. In this investigation, the incident wave is a plane wave travelling in a direction perpendicular to the screen. A Hertz vector formulation is used to reduce the electromagnetic problem to a system of scalar problems, which is shown to be governed by a pair of simultaneous integral equations of the second kind. The integral equations are valid for all wavelengths and are especially useful when the waves in both media have long wavelengths compared with the radius of the aperture. Low frequency approximations to the tangential components of the electric field in the aperture, the transmission coefficient, and the backscatter coefficient are obtained.
Effect of rotation and a general oblique magnetic field on Kelvin–Helmholtz instability
Authors: Sharma R. C. , Srivastava K. M.
Published: April 2011

In the present paper, we study the effect of rotation and of an oblique magnetic field on Kelvin–Helmholtz instability. The dispersion relation has been derived for the case of equal densities and different velocities. It is found that the magnetic field has a stabilizing effect, even in the presence of rotation.
Ge(Li)–Ge(Li) gamma-ray coincidence studies of the decay of 18.6 h 159Gd
Authors: Brown R. A. , Roulston K. I. , Ewan G. T. , Andersson G. I.
Published: April 2011

The gamma-ray spectrum of 159Tb following the β decay of 18.6 h 159Gd has been studied with high resolution Ge(Li) detectors. Eighteen transitions were observed, two of which are reported here for the first time. The previously reported complex nature of the 617 keV transition has been examined and high resolution studies have revealed a doublet structure with energies 616.5 ± 0.3 and 617.7 ± 0.2 keV and intensities of (2.3 ± 0.6) × 10−3% and (15.0 ± 2.3) × 10−3% per disintegration respectively. Gamma–gamma coincidence experiments were performed with large volume coaxial and thin window planar Ge(Li) detectors, using the related address technique and on-line computers. These experiments have established levels at 58, 138, 348, 363, 581, 618, 674, and 855 keV. All of the transitions observed in the direct spectrum have been fitted into the level scheme.
A source of 3.85-MeV gamma rays for testing Ge(Li) detectors
Authors: Litherland A. E. , Alexander T. K. , Jeffs A. T.
Published: April 2011

Mono-energetic 3.85-MeV gamma rays, and lower energy gamma rays, have been produced in a source consisting of an intimate mixture of 10B and PuO2. Levels in 13C are excited by the 10B(α,pγ)13C reaction and the Doppler broadening of gamma rays from the 3.85-MeV level is attenuated, since its lifetime is long compared with the slowing-down time of 13C ions in the source material. When observed with a particular 15-cm3 Ge(Li) detector, the 3.85-MeV full-energy peak had a width of 4.5 keV(FWHM), consistent with no Doppler broadening. The measured energy of the gamma ray from the third excited state of 13C is 3854 ± 1 keV. The branching ratios I(3854 → 3090)/I(3854 → 0) = 2.5 ± 0.5 × 10−2 and I(3854 → 3685)/I(3854 → 0) = 0.55 ± 0.03 have been determined using the source.
Enhancement of superconductivity in thin aluminium films
Authors: Cherney O. A. E. , Shewchun J.
Published: April 2011

The results of superconductive tunneling measurements are presented, on very thin (35–80 Å) aluminium films which exhibit enhanced transition temperatures Tc up to 2.16 °K, and also exhibit a unique energy gap. Stability of the enhanced Tc films is attained by investigating the films in a vacuum; however, upon breaking vacuum, oxide growth occurs, and the tunneling barrier becomes impenetrable. The temperature dependence of the energy gap is BCS-like, and the BCS gap parameter 2Δ(O)/kBTc lies within experimental error of the usual BCS value of 3.528 for a weakly coupled superconductor. Existing theories of the enhancement of Tc are discussed in the light of present experimental evidence. However, it is found that none are capable of explaining reasonably the experimental data accumulated to date. It appears that all thin film systems reported to date as having shown an enhancement of Tc are basically the same. Electron microscope photomicrographs show that, structurally, the films are composed of crystallites having a wide range of sizes. Any new theory will have to contain a volume density of such crystallites as a key parameter in determining the enhanced Tc of the film.
Jahn–Teller effect in the Cr3+ ion in a tetrahedral environment
Authors: Rai R. , Savard J.-Y. , Tousignant B.
Published: April 2011

The ground level of the Cr3+ ion in a tetrahedral environment is analyzed. In particular, it is shown that the calculation based on an undistorted tetrahedral ligand field yields a Γ7 level in the ground state whereas the ground state in the presence of a dynamic Jahn–Teller effect (vibrational E mode) of strength given by EJT > 8a, where EJT is the Jahn–Teller energy and a is a second-order spin–orbit coupling parameter, is aΓ8. The expected nature of electron spin resonance spectra is discussed.
Stimulated emission from normal to superconducting metal junctions
Authors: Leopold L. , Gregory W. D. , Bostock J.
Published: April 2011

Stimulated radiative emission at the gap frequency in superconductors due to quasi-particle pairing is found to be more likely than stimulated phonon emission. Threshold conditions for lasing have been calculated. The range of several parameters for which radiation may be expected is presented.
Crystal fields in the interpretation of the spin Hamiltonian of 6S ions
Authors: Sharma R. R.
Published: April 2011

It is shown that the crystal field used in an earlier investigation for explaining the axial field splitting of the Mn2+ ion in MnF2 and ZnF2 has no error as inferred by a later author. This is proved with the help of the transformation properties of the crystal field. Hence, the agreement between the theory based on the point-multipole model and experiment is still valid.
Pulsed n.m.r. in nickel
Authors: Koster E. , Turrell B. G.
Published: April 2011

The dependence of the n.m.r. free induction decay amplitude on the strength of the r.f. field and on pulse length has been studied in nickel metal powder. The results can be explained by the model of Stearns and Overhauser which hypothesizes boundary pinning of domains. We estimate a maximum enchancement factor in nickel of [Formula: see text].
Inelastic collisions between excited alkali atoms and molecules. VI. Sensitized fluorescence in mixtures of sodium with CH4, CD4, C2H2, C2H4, and C2H6
Authors: Stupavsky M. , Krause L.
Published: April 2011

The total cross sections for 32P1/2–32P3/2 mixing in sodium, induced in collisions with CH4, CD4, C2H2, C2H4, and C2H6 molecules, have been determined using the method of sensitized fluorescence. The sodium vapor – molecular gas mixtures were irradiated with each NaD component in turn, and the cross sections were obtained from measurements of relative intensities of the two D components present in the fluorescent light. The cross sections are as follows. For CH4: Q12(2P1/2 → 2P3/2) = 148 Å2, Q21(2P1/2 ← 2P3/2) = 77 Å2; for CD4: Q12 = 151 Å2, Q21 = 81 Å2; for C2H2: Q12 = 182 Å2, Q21 = 96 Å2; for C2H4: Q12 = 178 Å2, Q21 = 94 Å2; for C2H6: Q12 = 182 Å2, Q21 = 95 Å2. The cross sections Q21 are in good agreement with the values calculated according to the theory of Callaway and Bauer.
Observation of the d1Σ+–b1Σ+ system of NH and ND in the vacuum ultraviolet
Authors: Whittaker F. L.
Published: April 2011

New emission bands of NH at 1708.4 Å, 1801.0 Å, and 1814.4 Å and ND bands at 1683.1 Å, 1695.2 Å, 1750.4 Å, 1761.0 Å, and 1771.9 Å are assigned to the d1Σ+–b1Σ+ transition. Revised vibrational constants (in cm−1) for the b1Σ+ state are ωe = 3347(NH), 2447.5(ND), ωexe = 70.7(NH), 37.9(ND).
On the photodisintegration of nickel isotopes
Authors: Pai H. L. , McNeill K. G.
Published: April 2011

The anomalies in the photoneutron cross sections of 58Ni and 60Ni found by Min and White are explained in terms of compound nucleus calculations using shell independent parameters.
Photodisintegration of the alpha particle with tensor forces and a velocity-dependent potential
Authors: Jain S. C.
Published: April 2011

We calculate the integrated cross section (σint) and the bremsstrahlung-weighted cross section (σb) for the photodisintegration of the alpha particle by applying the sum rules of Levinger and Bethe. The two-body interaction is assumed to be a mixture of a central part, having a velocity-dependent term, and a tensor part. The ground-state wave function of the alpha particle is taken to be a mixture of the principal 1S0 and 5D0(1) states, whose parameters are obtained from a variational calculation of the binding energy of the alpha particle with the above potential. We find our results for σint and σb to be in reasonable agreement with the experiments.
Symmetry properties of the normal modes of vibration of calcite and α-corundum
Authors: Cowley E. R.
Published: April 2011

A group theoretical analysis is carried out on the symmetry properties of the normal modes of vibration of crystals with the calcite and α-corundum structures. Both of these structures have the space group [Formula: see text]. The symmetry species present in the dispersion curves are determined for important wave vectors, and a transformation to block-diagonalize the dynamical matrix at the zone center is given.
Spin–spin interaction for some rare-earth ions
Authors: Malli Gulzari , Saxena K. M. S.
Published: April 2011

The spin–spin interactions are evaluated for Pr3+ (4f2), Nd3+ (4f3), Er3+ (4f11), and Tm3+ (4f12) using the expressions of the matrix elements of the spin–spin interaction for all the states arising from f2 and f3 electron configurations reported earlier by us.
Studies of auroral hydrogen emissions in west–central Canada. III. Proton and electron auroral ovals
Authors: Wiens R. H. , Jones A. Vallance
Published: April 2011

A chain of patrol spectrograph stations was operated from 1964 to 1965 to cover the geomagnetic latitude range 55° to 78 °N near geographic longitude 100 °W. Absolute intensities of hydrogen alpha and the OI(λ 5577) lines have been derived from over 7500 spectrograms. From this data, average Hα and λ 5577 zenith intensities, as a function of geomagnetic latitude and time, were derived. Results are also given for these averages for different ranges of Kp index. Plots were made of the λ 5577 intensities from which estimates of the night glow and proton-excited components had been subtracted. It was found that the center of the proton auroral oval lies a few degrees equatorward of that of the electron oval before midnight and crosses somewhat poleward of it after 0100 hours geomagnetic. The average proton and electron precipitation zones overlap considerably. With increasing magnetic disturbance, the proton precipitation zone spreads equatorward and increases considerably in its peak intensity, although its intensity is not very sensitive to Kp at geomagnetic latitudes above 70°. For low Kp, the Hα intensity distribution is rather symmetrical about midnight, but for high Kp the intensities are highest before midnight and the proton auroral oval has its maximum equatorward extent around 2100 hours.
Doppler observations of associated ionospheric and magnetic fluctuations
Authors: Boyd G. M. , Duffus H. J.
Published: April 2011

Observations of ionospheric motions associated with magnetic micropulsations were conducted during a three-year period.Current theoretical models of the interaction indicate that observable Doppler shifts of high-frequency radio waves coherently reflected from the ionosphere should accompany all reasonably large geomagnetic disturbances, and vice versa, but this is not observed. Detailed studies of particular classes of events were therefore undertaken, involving spectral analyses, cross correlations, diurnal and seasonal occurrence statistics, and studies of associations with various types of ionospheric and magnetic records.Certain classes of magnetic pulsation events are found to be directly associated with F-region motions. Of the many possible mechanisms which may be responsible for these associations, two stand out as prime candidates: (i) hydromagnetic waves and (ii) neutral-gas waves modulating ionospheric electrojets. At mid-latitudes during quiet-sun years, the direct effects of precipitation of charged particles appear to be of much less importance.
Properties of the 1.763 MeV level in 35Cl
Authors: Taras P. , Matas J.
Published: April 2011

Angular distribution and linear-polarization measurements have been performed at the Ep = 3.115 and 3.345 MeV resonances in the reaction 35Cl(p,p′γ)35Cl. The spin and parity of the 1.763 MeV level in 35Cl have been deduced to be 5/2+ while the multipolarity mixing ratio of its decay to the ground state has been found to be δ(E2/M1) = +2.64 ± 0.12. These results confirm that the possible E1 transition from the 3.163 to the 1.763 MeV level in 35Cl is inhibited by a factor of at least 108. The properties of the 1.763 MeV level and the beta decay from 35Ar to the first three levels in 35Cl are found to be in quite good agreement with the predictions of the unified model.
Effect of a magnetic field and Coriolis forces on Rayleigh–Taylor's instability
Authors: Gandhi J. M.
Published: April 2011

We present variational principles which characterize the solution of the equilibrium of a plane horizontal layer of an incompressible, electrically conducting fluid of electrical conductivity σ e.m.u., of magnetic permeability K, having a variable density ρ(z) in the vertical z direction, which is also the direction of gravity having acceleration g, and of viscosity μ(z) and which is rotating at Ω radians per second about the vertical axis in the presence of a horizontal magnetic field for the two cases:(i) When the electrically conducting fluid is assumed to be nonrotating (Ω = 0), with the conductivity σ being finite and the horizontal magnetic field being uniform.(ii) When the electrically conducting fluid is assumed to be rotating (Ω ± 0), with the conductivity σ being infinite and the horizontal magnetic field being stratified.Based on the variational principles for these two cases, an approximate solution is obtained for the special case of a fluid of finite depth d stratified according to the law ρ0 = ρ1 exp βz (ρ1 and β are some constants), for which kinematic viscosity ν is assumed to be constant. Growth rate and total wave number of the disturbance are related by two cubic equations, and for simplified cases explicit solutions are obtained. The properties of hydromagnetic waves generated are discussed.
Analysis of thermal glow curves in rare-earth-doped CaF2 crystals
Authors: Schlesinger M. , Menon A. Krishna
Published: April 2011

The main parameters, that is, thermal activation energies, frequency factors, and order of kinetics, are calculated for some glow peaks in rare-earth-doped CaF2. From the results, it is inferred that the hole trapping sites are in close proximity to the rare-earth ions.
Rotational analysis of the 0,2 band of the 11BO α system
Authors: Dunn T. M. , Hanson Louise Karle
Published: April 2011

The 0,2 band of the α system of 11BO has been carefully analyzed under very high resolution and the following constants were obtained (in cm−1):[Formula: see text]The analysis enables the sign and magnitude of the spin doubling constants γν′ of the B2Σ+ state to be obtained.
Electroreflectance measurements in mixed III–V alloys
Authors: Vishnubhatla Sarma S. , Eyglunent Bernard , Woolley John C.
Published: April 2011

Electroreflectance measurements by the electrolyte technique have been made on alloys of the InAsxSb1−x, InAs1−xPx, and GaxIn1−xSb systems and the variation of the values of E1, E1 + Δ1, E0′, and E2 found as a function of composition x. These results have been analyzed together with those previously published for the GaAs1−xPx and GaxIn1−xAs alloys. It is found that in all five cases, the deviation from linearity of the E versus x curves must be attributed mainly to the effects of disorder in the alloy lattice. For each curve, a parameter measuring the effect of disorder has been determined and the results are discussed in terms of the band structure of the alloys.
Steady radiation fronts behind windows
Authors: Ahlborn Boye , Zuzak William W.
Published: April 2011

If radiation of constant intensity W ionizes a gas of density ρ1 behind a window, a steady radiation front may be established and the gas will be heated, accelerated, and compressed. The properties of such radiation-induced waves are discussed as a function of the external parameters W and ρ1. With high absorber density ρ1 the radiation front acts like a "leaky piston" accelerating and compressing the neutral gas ahead, and leaving plasma of reduced density behind. This leads to the formation of a precursing shock wave travelling at vshock α (W/ρ1)1/3. The shock develops as a sharp spike near the Jouguet point which requires a sonic speeds a4 α (W/ρ1)J1/3in the ionized gas. With lower absorber density, the radiation front propagates as vr α W/ρ1 and accelerates and compresses the ionized gas at its rear. This plasma is then brought to rest and expanded in a subsequent rarefaction wave.
Stimulated thermal scattering in isotropic media. II
Authors: Enns R. H. , Batra I. P.
Published: April 2011

A rigorous theoretical treatment of stimulated thermal scattering for an isotropic medium in the second-sound limit is presented. The validity conditions for the theory are thoroughly investigated and the saturation and depletion effects are included. We have calculated a critical absorption coefficient; a comparison of this with the experimental value would provide a test for the theory and indirect evidence for the onset of second sound. The threshold condition on the incident laser field strength has also been derived.
Absorption spectrum of the NO molecule. IX. The structure of the f complexes, the ionization potential of NO, and the quadrupole moment of NO+
Authors: Jungen Ch. , Miescher E.
Published: April 2011

The 0–0 bands at 1474 Å and 1422 Å of the first two members of the nf–X2Π Rydberg series of NO have been observed under high resolution in the absorption spectrum of cold nitric oxide gas. They show an abnormal rotational structure which has been analyzed with the help of a computer program. The uncoupling of the angular momentum l = 3 of the f electron in the rotating molecule is discussed theoretically, including the effect of electron spin and interaction with the molecular core. The connection between the electronic energies TΛ of the f complex in the nonrotating molecule and the electronic energies [Formula: see text] in the rapidly rotating molecule is given. From the analysis a precise value of the ionization potential of NO is obtained, viz. T∞ = 9.2639 ± 0.0006 eV, and the quadrupole moment of the molecular ion NO+ is determined to be Qzz = +(0.79 ± 0.06) 10−26 e.s.u. cm2. The "atomic" and the "molecular" properties of a highly excited molecular Rydberg electron are discussed.
Electron recombination and diffusion in CO at elevated temperature
Authors: Mentzoni Michael H. , Donohoe James
Published: April 2011

The electron time decay in an afterglow following a short pulsed d.c. discharge in CO has been investigated using microwave diagnostic techniques. The gas was heated to an average temperature of 775 °K. Two-body electron-ion recombination and ambipolar diffusion were found to be the only important electron removal mechanisms present in the pressure interval [Formula: see text] Torr with the rate constants αr = 3.9 × 10−7 cm3 s−1 and Dap0 = 372 cm2 s−1 Torr respectively. If we postulate a T−γ dependence for αr, comparison with room temperature results yields γ = 0.57. The diffusion coefficient appears to increase strongly with temperature based upon an estimated zero field mobility for CO+in CO at 273 °K found in the literature.
Color centers and interstitials in X-irradiated NaCl crystals
Authors: Nest J. P. Van , Hutchison T. S. , Rogers D. H.
Published: April 2011

Irradiation by X rays of NaCl crystals produces F centers and interstitial ions. The former are detected by measured changes in optical absorption, the latter by measured changes in the velocity of sound. A simple theory of dislocation pinning by interstitials accounts well for the changes in acoustic velocity. Current theories of initial-stage and final-stage coloration are justified by the results; estimates of the rates of defect production are made.
Decay of 185Os
Authors: Cook W. B. , Johns M. W.
Published: April 2011

The energies and intensities of 10 transitions in 185Re following the decay of 185Os have been determined using Ge(Li) detectors and a magnetic beta-ray spectrometer. Internal conversion measurements made at a resolution of 0.15% in momentum have yielded the multipole character of the 9 strongest transitions. The proposed decay scheme has been tested by a two parameter γ–γ coincidence experiment. The decay energy has been found to be 1012 ± 3 keV from γ–X coincidence measurements involving the 646, 717, 875 + 880, and 931 keV transitions.
Radiative recombination rate of donor–acceptor pairs
Authors: Novotny V.
Published: April 2011

The radiative recombination rate of electrons trapped on donors with holes trapped on acceptors is theoretically investigated in the effective-mass approximation for direct transitions in the cases when interband dipole transition is allowed and also when it is forbidden.
On the relation between perturbation theory and distribution function theories of liquids
Authors: Chen M. , Henderson D. , Barker J. A.
Published: April 2011

Perturbation theory of liquids and distribution function theories of liquids (as typified by the Percus–Yevick theory) are examined. It is shown that the energy equation, relating the pair distribution function to the internal energy, may be integrated to yield an expression for the free energy which is similar to that obtained from perturbation theory. The equation of state resulting from this approach, based on the energy equation, is shown to be better than that obtained from the pressure or compressibility equations. Finally, the similarity between perturbation theory and distribution function theories is exploited to provide simple improvements to either approach.
Debye temperatures of 24 cubic elements by three methods
Authors: Konti A. , Varshni Y. P.
Published: April 2011

The Debye characteristic temperatures of 24 cubic elements have been calculated from their elastic constants by the Hopf–Lechner method, the Houston–Bhatia–Tauber method, and the Fedorov method, to various degrees of approximation. The calculated values have been compared with the experimental ones and the relative merits of the three methods discussed.
Neutron activation resonance integrals of 64Zn, 68Zn, 85Rb, 100Mo, 102Ru, 113In, 123Sb, and 180Hf
Authors: Ricabarra M. D. , Turjanski R. , Ricabarra G. H.
Published: April 2011

The ratio of resonance integral to thermal activation cross sections of the isotopes 64Zn, 68Zn, 85Rb, 100Mo, 102Ru, 113In, 123Sb, and 180Hf relative to gold has been determined by measuring cadmium ratios.The standard gold or a secondary standard was mixed uniformly in the samples and the activities resolved with a lithium-drift germanium γ-ray spectrometer. Expressed as Westcott S0 values the results were: 64Zn = 2.06 ± 0.03, 68Zn = 3.72 ± 0.14, 85Rb = 18.4 ± 0.6, 100Mo = 21.7 ± 0.8, 102Ru = 3.76 ± 0.03, 113In = 24.7 ± 0.5, 123Sb = 28.3 ± 2.1, 180Hf = 2.17 ± 0.09. All measurements are relative to S0 = 17.7 for gold.
II. Cosmic-ray latitude survey in Canada in December, 1965
Authors: Carmichael H. , Bercovitch M.
Published: April 2011

This, the second paper of a set of five, describes a small latitude survey, made in Canada in December, 1965, while the intensity of cosmic radiation was still within one per cent of its IQSY maximum. Flat sites at airports were used in the hope of eliminating environmental effects noted in the 1965 summer survey and particular care was taken to verify the barometric data. The objective was to improve upon the summer measurements as regards the boundary of the high-latitude plateau of the neutron-monitor intensity and it is believed that an intrinsic accuracy within 0.1% was achieved, but it was found that the NM-64 neutron-monitor counting rate was decreased about 0.5% by the presence of snow on the ground. The intensity near sea level appeared to be constant to the southern boundary of the survey at Windsor Airport (1.56 GV). The two most southerly sites, Windsor and Toronto (1.33 GV), were snow-free.
III. Cosmic-ray latitude survey in Western USA and Hawaii in summer, 1966
Authors: Carmichael H. , Shea M. A. , Peterson R. W.
Published: April 2011

A 3-NM-64 neutron monitor and a 2-MT-64 muon monitor were operated at 29 sites near sea level and on mountains on the western seaboard of the USA and in Hawaii in May, June, and July, 1966, in continuation of the latitude survey begun in 1965 and reported in papers I and II of this set of five papers. The original results and also the corrections for temperature structure of the atmosphere and for secular variations of the cosmic radiation are given in detail. While the overland equipment was at its highest altitude on Mt. Hood (2.4 GV) and on the summits of Mt. Palomar (5.7 GV) and Mt. Haleakela (13.3 GV), an airborne neutron monitor was operated at seven different levels between 3000 m and 12 000 m. The pressure-measuring equipment and also the neutron monitor in the aircraft were calibrated in terms of the overland instruments while the aircraft was at the same altitude as the overland equipment on the summit of Mt. Haleakela.
Investigation of the hyperfine structure of the 62P3/2 state of 133Cs by a level-crossing method
Authors: Violino P.
Published: April 2011

The hyperfine structure of the 62P3/2 state of 133Cs has been studied using the level-crossing method with an unconventional experimental arrangement. The value of the hyperfine structure constant A was found to be 50.45 ± 0.08 MHz.
Coupling a scintillator to a small photosensitive area
Authors: Daniels J. M. , Tsui Laura Y. C.
Published: April 2011

A model is developed to describe a scintillation counter coupled to a photosensitive area which is small in comparison with the dimensions of the scintillator. It is shown that the reciprocal of the pulse height is a linear function of the reciprocal of the photosensitive area, and that the constants in this relation are determined by the albedo of the material surrounding the scintillator and by the refractive index of the medium coupling the window to the photosensitive device. This relation has been verified experimentally.
New spectrum of the SiO+ molecule—a correction
Authors: Dunn T. M. , Rao K. M. , Nagaraj S. , Verma R. D.
Published: April 2011

A spectrum previously attributed to SiO+ has been shown to be due to SiN. The sign of the spin doubling of the ground state has been determined and more accurate constants obtained than previously.
Admittance of an infinite cylindrical antenna immersed in a lossy, compressible plasma
Authors: Monroe Richard L.
Published: April 2011

An expression is derived for the driving point admittance of an infinite, perfectly conducting cylindrical antenna excited by a finite uniform gap and immersed in a lossy, compressible, isotropic plasma. This expression is based on the twin assumptions that the gap width is much smaller than the wavelength of the plasma (electroacoustic) wave and that the radius of the antenna is much smaller than the wavelength of the electromagnetic wave; it is similar in form to the corresponding expression for an infinite antenna in free space, and it is obtained in much the same manner. Conductance and susceptance curves computed from the admittance function are in good agreement with those obtained numerically by other authors for f ≥ 0.7 fP. The behavior of the admittance function at frequencies in the neighborhood of the plasma frequency depends mainly on the electron – neutral particle collision frequency, not the plasma temperature. In general, the effect of the temperature is quite small, although a temperature-related effect can produce large admittance values in very low-loss plasmas at frequencies well below the plasma frequency (f ~ 0.03 fP for T = 1500 °K). This investigation supports the view that the propagation constant of the current along a cylindrical antenna in a compressible plasma is nearly equal to the plane-wave propagation constant in an incompressible plasma.
Radio-wave propagation to the antipode
Authors: Gerson N. C. , Hengen J. G. , Pipp R. M. , Webster J. B.
Published: April 2011

A two-year (1960–1961) experiment was undertaken between Perth, Australia, and Bermuda to test the hypothesis of an antipodal focus for high-frequency radio waves.The transmitting and receiving sites were antipodal to within one degree in latitude and longitude. Three frequencies: 5, 16, and 30 MHz were utilized. Results indicate a definite intensity enhancement at the antipode, with best reception found for the center frequency. At the 48 percentile level, reception persisted for 24 h in December and 8 h in June. Reception at 5 and 30 MHz was mainly constrained to two periods a day of 3–5 h each, centered near ground sunrise and sunset. Reception at the antipode was superior to that at two other stations, each located about 1700 km closer to the transmitter. Characteristic changes in the signal intensity were marked around sunrise and evident around sunset. These included a presunrise minimum in percent reception (30–70 min prior to ground sunrise), followed by a steep ascent to a postsunrise maximum within 60 min after ground sunrise. Azimuths of arrival at 16 MHz avoided the sector ± 90° around the bearing of the subsolar point but favored those ± 90° around the bearing of the subsolar nadir point. The predominant sector of arrival rotated through 360° in 24 h. Reception was poorest over paths intersecting the polar caps and best over paths having the greatest extent over water. Few of the results could have been derived from the standard predictions for the most usable frequency.Because of the high intensities involved, it is believed that ionospheric ducting and superrefraction, in addition to some multihop propagation, are probable mechanisms.
Equilibrium theory of the nuclear symmetry energy of infinite nuclear matter
Authors: Weiss Richard A. , Cameron A. G. W.
Published: April 2011

A set of generalized nuclear matter curves is calculated as a function of density and ξ = 1−(2Z/A), which maps out the energy versus density plane for 0 ≤ ξ ≤ 1 and determines the nuclear matter equilibrium curve (NMEC) as the locus of their saturation points. The NMEC immediately determines the equilibrium energy and density as a function of the neutron excess, and thereby automatically gives the nuclear symmetry energy. The component parts of the equilibrium energy are also determined, and we find that the average kinetic energy per nucleon is a decreasing function of the neutron excess parameter, so that the contribution of the kinetic energy to the second order coefficient, β2∞, is negative. By noting that the density variation along the NMEC is determined by kFE = k∞(1−F2ξ2 + F4ξ4−… ) f−1 with k∞ = 1.4 f−1, F2 ~ 0.45, and F4 ~ 0.07, we find a general connection between the equilibrium and nonequilibrium symmetry energy coefficients, i.e. β0∞ = β0NE(k∞), β2∞ = β2NE(k∞), β4∞ = β4NE(k∞)[Formula: see text], etc., where K0(2) is the standard nuclear compressibility. We find a large negative value for the fourth order coefficient, β4∞ ~ −25 MeV, and a large positive value for the sixth order coefficient, β6∞ ~ 15 MeV, while the corresponding nonequilibrium values of these two coefficients are small and positive. Nuclear matter systems with neutron excess are found to be more bound than is predicted by constant density calculations, and we find that a negative isospin compression energy term is required to be added to the previous constant density calculations.
Equilibrium theory of the symmetry energy of finite nuclei
Authors: Weiss Richard A. , Cameron A. G. W.
Published: April 2011

The nuclear symmetry energy of finite nuclei is calculated first in a nonequilibrium scheme in which the binding energy is a function of the central density parameter as well as the mass number and neutron excess parameter, i.e. E(kc, A, ξ), and then in an equilibrium scheme with the central density parameter given as a function of A and ξ in the form kcE(A, ξ) = kc0(1 + q1ξ−q2ξ2 + q3ξ3−q4ξ4 + … ), where kc0 = k∞(1 + ρ0) f−1 and the qj(A) and ρ0(A) depend on Coulomb and surface effects. In the equilibrium scheme, the symmetry energy coefficients are functions of mass number. A connection is made between the symmetry energy coefficients as calculated in the nonequilibrium (NE) and equilibrium schemes, and we find these coefficients to be, β0(A) = β0NE(kc0), β2(A) = β2NE(kc0)−[Formula: see text], etc. We find that the fourth order coefficient β4(A) is large and negative for all A, and is about −47 MeV in the region A ≈ 125 which agrees reasonably well with the −37 MeV value predicted by the Cameron–Elkin exponential mass formula. No linear term is found in the symmetry energy, but third, fifth, and higher order odd symmetry energy coefficients are found to be present. The alternation of the signs of the symmetry energy coefficients as well as the density expansion coefficients are in accordance with Le Chatelier's principle. As in the case of infinite nuclear matter, we find that the binding energy of nuclei with neutron excess is larger than that calculated assuming constant density, and that a negative isospin compression energy must be added to the constant density calculation of the energy if the correct binding is to be predicted. Finally, the general expression for the symmetry energy coefficients of order j is[Formula: see text]
Relaxation of uniform rarefied gas coupled to a thermal bath
Authors: Grmela M. , Votruba J.
Published: April 2011

An exact mathematical discussion is given of the spectrum of the operator governing the time evolution of the uniform rarefied rigid-sphere gas coupled to a thermal bath. Adapted methods, developed in the neutron thermalization theory and rarefied-gas dynamics, are used. Two cases are discussed in some detail: the thermal bath consists of gas particles of mass much smaller than the particles of the considered rarefied gas (i.e. the Brownian motion of the rarefied gas) and the thermal bath consists of gas particles of the same mass as the particles of the rarefied gas. The results are interpreted physically in connection with the possibility of a macroscopic description of the system.
E3 Coulomb excitation of 19F
Authors: Alexander T. K. , Häusser O. , Allen K. W. , Litherland A. E.
Published: April 2011

The E3 matrix element connecting the ground state with the 5/2−, 1346-keV level in 19F has been measured by projectile excitation of a 19F beam and observation of the 1236-keV de-excitation gamma ray in Ge(Li) detectors. The thick-target yield of the 1236-keV gamma ray was 1.6, 6.0, 9.8, and 23 gammas per 1010 projectiles at bombarding energies of 22, 25, 26, and 28 MeV, respectively. The average value of the strength of the E3 transition deduced from these measurements is [Formula: see text] In addition, the E2 Coulomb-excitation cross section of the 1554-keV level was measured and the reduced transition strength of the E2 transition from the 1554-keV level to the ground state was found to be 6.8 ± 0.7 W.u. Comparisons are made with model predictions.
High-power microwave double-resonance experiments
Authors: Oka Takeshi
Published: April 2011

Several microwave double-resonance experiments using high pumping power have been carried out in ethylene oxide molecules. The characteristics of the double resonance, such as the splitting or the "pulling" of the signal, have been observed magnified by the use of high power. The M fine structure of the signal has been observed for the first time. By the use of collision-induced transitions, the formula of Karplus and Schwinger for saturation has been confirmed at the high-power level. Applications of the technique for additional studies of molecular problems are discussed.
A nonlinear modification of Maxwell's equations
Authors: Schiff H.
Published: April 2011

Starting with the point-charge solutions of Maxwell's equations, a nonlinear modification is developed which results in a conformally invariant system. Nonsingular solutions exist representing discrete neutral and charged states with zero mass. A method of breaking conformal invariance is suggested. The resulting system has a number of properties similar to the conformally invariant one, including the existence of a globally conserved action scalar.
Nuclear g factors of three levels of 192Pt
Authors: Kenyon D. B. , Keszthelyi L. , Cameron J. A.
Published: April 2011

The g factors of the 316, 612, and 785 keV levels of 192Pt have been measured using gamma–gamma angular correlations perturbed by the hyperfine field in an iron alloy. Sources were 192Ir in 1 at.% Ir Fe alloy. Coincidences were observed using a combination of Ge(Li) and scintillation detectors. For the three levels, the g factors obtained were[Formula: see text]In addition, the E2/M1 mixing ratios were obtained from the angular correlation measurements.[Formula: see text]
The use of saturation dip absorption in microwave spectroscopy and in microwave frequency stabilization
Authors: Costain C. C.
Published: April 2011

An experiment is described which shows that the saturation dip technique (often termed the Lamb dip, in the laser field) can be used at microwave frequencies to identify the centers of absorption lines very precisely. The use of this technique in microwave spectroscopy is illustrated and the possibility of using this technique to stabilize oscillators is discussed.
Thermal expansion of the noble metals below 15 °K
Authors: Kos J. F. , Lamarche J. L. G.
Published: April 2011

We describe the design of a dilatometer having a sensitivity of about 10−11 cm/cm and present some results of its use in measuring the thermal expansion of copper, silver, and gold in the region 4.2 to 15 °K.
Lifetimes of low-lying states in 28Si
Authors: Bister M. , Anttila A. , Räsänen J.
Published: April 2011

The lifetimes of the four first excited energy levels of 28Si have been measured using the Doppler-shift attenuation method in the 27Al(p,γ)28Si reaction. In the analysis of the Doppler-shift data, the effect of the inelastic large-angle collisions in the slowing-down process was estimated in addition to the conventional treatment.
Conduction bands of GaxIn1–x Sb alloys
Authors: Coderre William M. , Woolley John C.
Published: April 2011

Measurements of Hall coefficient and electrical conductivity have been made on alloys of the system GaxIn1–xSb over a range of temperature from 100 °K up to 950 °K or to 20° below the solidus temperature of the particular specimen, whichever was the lower. These data have then been analyzed in terms of equations involving three conduction and two valence bands, the important unknown parameters in the equations being determined by a trial and error fitting technique. The results give the variation of the energy separation from the valence band of the [Formula: see text] and [Formula: see text] conduction band minima, as well as the main (000) band gap as a function of the composition and temperature. Also determined from the analysis are the (000) electron mobilities, which are found to vary linearly with composition, indicating that alloy scattering has negligible effect on the mobility values.