bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron paramagnetic resonance experiments with Ti3+ ions in CsAl(SO4)2∙12H2O
Authors: Woonton G. A. , MacKinnon John A.
Published: April 2011

Measurements are reported on single crystals of cesium aluminium alum containing Ti3+ ions in concentrations between 0.05 and 0.5 %.Three nonequivalent complexes are located with the z axis along each of the four cube diagonal directions, that is, there appear to be 12 possible sites for a complex in each unit cell. The effective g factors for the three nonequivalent sets of complexes are shown below:[Formula: see text]The lines due to complex I are asymmetrical and have a width of from 50 to 100 Oe, these lines being similar to those reported for the Ti3+ complex in corundum. The lines due to complex III are symmetrical and have a width between 150 and 200 Oe.
Action d'un champ magnétique de faible intensité sur les échos de spins électroniques
Authors: Dupont M. , Woonton G. A.
Published: April 2011

not available
Edge condition and "intrinsic loss" in uniaxial plasma
Authors: Lee S. W. , Mittra R.
Published: April 2011

The electromagnetic field behavior near the edge of a conducting wedge in contact with a uniaxial plasma is investigated. The static magnetic field in the plasma is assumed to be perpendicular to the edge. Explicit expressions are obtained for the eigenvalue t which governs the edge behavior. The nonresonance case is treated first and the results are extended subsequently to the resonance case via analytic continuation of the functions involved, using a three-sheeted Riemann surface. The behavior of t is found to be distinctly different in the resonance case from either the isotropic or the nonresonance case in that singularities at the edge now occur for a certain range of the external angle of the conducting wedge, less than π. It is also found that "intrinsic losses" may occur for certain parameters in a purely lossless resonance plasma. However, the degenerate surface wave discussed by earlier workers does not accompany the intrinsic-loss phenomenon as it does for a parallel orientation of the d-c. magnetic field investigated by the above workers. Consequently, it is no longer possible to explain the intrinsic loss in terms of energy transported by the degenerate surface wave. A possible resolution of this difficulty is suggested for an ideally lossless medium via the derivation of a mathematical solution which does not display any intrinsic losses, and hence, satisfies the energy condition in such a system. The slightly lossy case is examined in detail and it is shown that in the presence of some loss in the medium, however slight, large energy losses are expected to occur in the neighborhood of the edge. Nevertheless, these losses are explainable and should not be regarded as "intrinsic".
A neutron-diffraction study of the α phase in the palladium–gold–hydrogen and palladium–gold–deuterium systems
Authors: Maeland Arnulf J.
Published: April 2011

It has been shown previously that both hydrogen and deuterium in β phase Pd–H and Pd–D are situated in the octahedral interstices of the f.c.c. palladium lattice, but attempts to determine the atomic positions in the α phase proved inconclusive, since only small amounts of gas are contained in this phase at room temperature. In order to locate the hydrogen atoms in the α phase by neutron diffraction the concentration must be increased. This can be accomplished by increasing die temperature and gas pressure. However, another method which avoids the use of high temperature and pressure was used in this investigation. This method is based on the observation that the addition of gold or silver to palladium results in increased hydrogen solubility in the α phase. Our neutron diffraction results on powdered α phase gold–palladium–hydrogen and gold–palladium–deuterium samples show that both hydrogen and deuterium are located in the octahedral positions of the f.c.c. metal lattice. It seems reasonable to assume that the same positions are occupied in the α phase of Pd–H.
On the theory of multipole interactions
Authors: Gray C. G.
Published: April 2011

A simple derivation using group theory is given of the spherical harmonic expression for the most general multipole interaction between two charge distributions. Simplifications in the general expression which result when the charge distributions are of symmetrical shape are discussed.
Gamma photoconductivity of Al2O3
Authors: Huntley D. J. , Andrews J. R.
Published: April 2011

The electrical conductivity of single-crystal and sintered Al2O3 which occurs during bombardment with y rays has been measured in radiation fields up to 106 R/h, using a 60CO source. The conductivity was different for different crystals and the largest value observed was 0.7 × 10−16 (Ω-cm-R/h)−1; the value for ruby (Al2O3 + 0.05 % Cr2O3) was 100 times smaller. The filling of traps by electrons (or holes) manifested itself during the initial radiation of a specimen as a reduced conductivity until the traps were filled: the density and cross section of these traps were ~1017 per cm3 and ~10−17 cm2, respectively. The shape of the conductivity vs. time curve during the initial radiation is explained by a model which takes into account the excitation of electrons from traps into the conduction band by the energetic electrons resulting from the gamma radiation. It is shown that this model is able to account quantitatively for the observations, if it is assumed that the time required for a secondary electron to lose energy from 10 to 2 eV is somewhat longer than the time associated with the ionization of a filled trap. Conductivity glow curves were observed in all specimens using internal polarization of the specimens and at least four distinct traps were observed with energies in the range 1–2 eV; these are thought to arise from crystal structure defects.
The electron spin–lattice relaxation of a paramagnetic lattice defect
Authors: Walker M. B.
Published: April 2011

The introduction of a paramagnetic impurity into a diamagnetic host lattice results in changes in the force constants coupling the impurity to its nearest neighbors. We present a calculation which shows how the magnitudes of the coefficients b and c in the expressions T1 = bT−1 and T1 = cT−7 for the spin–lattice relaxation time of the impurity due to the direct process and the first-order Raman process, respectively, depend on the magnitudes of the aforementioned force constants. We give a formula for the spin–lattice relaxation rate in terms of temperature-dependent Green functions and establish a connection between these Green functions and the Green functions introduced into impurity problems by Lifshitz so that our calculations can be easily performed. The spin–lattice relaxation rate is evaluated to first order in the changes in force constants and at temperatures much below the Debye temperature. A conclusion of our work is that spin–lattice relaxation experiments (and probably also ultrasonic attenuation experiments) cannot be used to measure spin–lattice coupling coefficients directly unless there is reason to believe that the changes in the force constants are small. This paper is an extension of a previous work by the author on the spin–lattice relaxation of a simple mass defect, to the case of changes in force constants.
The temperature and frequency dependence of the inelastic neutron scattering from an Ising magnet
Authors: Allan G. A. T. , Betts D. D.
Published: April 2011

The magnetic inelastic scattering of neutrons from a spin-[Formula: see text] Ising system is considered. For the two-dimensional plane square lattice, the exact energy distribution of the scattering is obtained at all temperatures. It consists of a number of discrete levels, the envelope of which varies most markedly in the critical region. Some qualitative projections are also made concerning three-dimensional systems. For both two- and three-dimensional Ising models there can be no wave-vector dependence of the inelastic scattering function because there is correlation only between z components of the spins on different sites.
The propagation of a transverse electromagnetic wave in a nonlinear, anisotropic, time-dependent plasma medium
Authors: Papa Robert J.
Published: April 2011

In a previous paper, a one-dimensional, inhomogeneous model was considered in describing the nonlinear interaction of a radiofrequency plane wave with a time-varying plasma. This paper extends the analysis to the anisotropic case, in which an elliptically polarized plane wave incident upon an electron-density profile induces changes in the electron density and electron temperature. A d-c. magnetic field parallel to the electron-density gradients causes the elliptically polarized wave to split into two distinct modes, a right-hand circularly polarized and a left-hand circularly polarized mode. The two modes are coupled through an energy-balance equation that governs the behavior of the electron temperature. The time-dependent response of the plasma may be found by numerically integrating an energy-balance equation and a continuity equation. The solution to the wave equation for the time-varying, inhomogeneous, anisotropic medium may be obtained through the use of the WKB approximation. The time scales for electron-temperature and electron-density changes are found to vary with incident flux, incident-wave ellipticity, and appropriate normalized plasma parameters.
Effect of ordering on the specific heat of Cu3Au below 3 °K
Authors: Martin Douglas L.
Published: April 2011

Ordering reduces the nuclear, electronic, and lattice specific heats. The change in nuclear specific heat supports the hypothesis that this term in the specific heat arises from the interaction of nuclear electric quadrupole moments with electric field gradients in the disordered lattice. The small (3.5%) change in the electronic specific heat suggests little change in the Fermi surface on ordering. The change in the lattice specific heat is greater than expected from elastic constant measurements on ordered and disordered Cu3Au.
Electrodynamics without potentials
Authors: Coombes Charles A.
Published: April 2011

By ascribing a mass to the photon a Lagrangian formulation of electrodynamics is obtained without the use of potentials. In the limit of the mass going to zero the standard results of electrodynamics are obtained. A unique method for calculating the commutator for an electron and a magnetic monopole also results.
Microwave spectrum of allyl cyanide (CH2=CHCH2CN)
Authors: Sastry K. V. L. N. , Rao V. M. , Dass S. C.
Published: April 2011

The microwave spectrum of allyl cyanide (3-butenonitrile) was studied in the region from 8 to 26 GHz. It was confirmed that this molecule exists in the two rotational isomers "cis" and "gauche". In the cis form, both a- and b-type transitions were assigned and the rotational constants in the ground vibrational state were calculated to be A = 11 323.01 + 0.08 MHz, B = 3739.20 ± 0.01 MHz, C = 2858.52 ± 0.01 MHz. The molecular dipole-moment components are μa = 3.26 ± 0.01 D, μb = 2.16 ± 0.05 D, and μt = 3.91 ± 0.03 D. For the gauche form, the a-type transitions were assigned and the rotational constants in the ground vibrational state are A = 17 295 MHz, B = 2619.91 ± 0.1 MHz, C = 2497.52 ± 0.1 MHz. The Stark effect measurement in this case gave the components of the dipole moment as μa = 3.69 ± 0.02 D, ub = 1.11 ± 0.06 D, μc = 0.98 ± 0.07 D, and μt = 3.98 ± 0.03 D.
High-temperature properties of the Ising model on the cristobalite lattice
Authors: Betts D. D. , Ditzian R. V.
Published: April 2011

The high-temperature properties of the Ising model on the cristobalite lattice are investigated by series expansion methods. The Curie temperature is found to be vl = tanh J/kTl = 0.2330 ± 0.003, the amplitude of the singularity in the susceptibility is Γ = 1.100 ± 0.001, the critical energy is −Ec/kTc = 0.268 ± 0.006, and the critical entropy is Sc/k = 0.548 ± 0.003. A comparison of critical parameters for the cristobalite and simple cubic lattices allows one to see the effect of structure for two lattices of the same coordination number.
Intensity of allowed and forbidden electron spin resonance lines of Mn2+ in tremolite
Authors: Manoogian A.
Published: April 2011

The angular variation of the intensities of the allowed and forbidden (Δm = ±1) electron spin resonance lines of Mn2+ impurities in tremolite, 2(H2Ca2Mg5(SiO3)8), was studied at room temperature and in the 9.2-GHz microwave frequency range. The crystalline electric field for the magnetic complex of Mn2+ in tremolite has orthorhombic symmetry, and this causes the line intensities to vary asymmetrically between the z and y magnetic axes. The experimental measurement of these intensities is in good agreement with the theoretical calculations of Bir (1964). Bir's theory has been used with success previously by others for ions in the higher-symmetry axial and cubic crystalline electric fields.
Lifetimes and decay modes of low-lying levels in 26Mg and 26Al
Authors: Häusser O. , Alexander T. K. , Broude C.
Published: April 2011

Several bound states with excitation energy up to 7 MeV were studied in 26Mg, using the 26Mg(p, p′γ) reaction. The attenuated Doppler shift of the de excitation gamma rays was observed with a Ge(Li) spectrometer. The extracted lifetime estimates and branching ratios for 15 excited states suggest that the rotational bands, built on different intrinsic states, are mixed considerably. Incidental information on lifetimes and decay properties of states in 26Al is also presented.
Inelastic collisions between excited alkali atoms and molecules. IV. Sensitized fluorescence and quenching in mixtures of cesium with N2, H2, HD, and D2
Authors: McGillis D. A. , Krause L.
Published: April 2011

6 2P1/2 ↔ 6 2P3/2 mixing and 6 2S1/2 ← 6 2P1/2,3/2 quenching in cesium, induced in collisions with ground state N2, H2, HD, and D2 molecules, have been investigated using techniques of sensitized fluorescence. Mixtures of cesium vapor and the gases, in which the cesium vapor pressure was kept very low to avoid multiple scattering, were irradiated with each component of the cesium resonance doublet in turn. The fluorescence which contained both components of the doublet was observed in a direction perpendicular to that of the exciting beam. Measurements of the relative intensities of the fluorescent components yielded the following cross sections for mixing and quenching. For Cs–N2 collisions: Q12(2P1/2 → 2P3/2) = 4.7 Å2, Q21(2P1/2 ← 2P3/2) = 25 Å2, Q10(2S1/2 ← 2P1/2) = 77 Å2, Q20(2S1/2 ← 2P3/2) = 69 Å2. For Cs–H2 collisions: Q12 = 6.7 Å2, Q21 = 44 Å2, Q10 = 7 Å2, Q20 = 5 Å2. For Cs–HD collisions: Q12 = 4.8 Å2, Q21 = 32 Å2, Q10 = 4 Å2, Q20 = 3 Å2. For Cs–D2 collisions: Q12 = 4.2 Å2, Q21 = 28 Å2, Q10 = 8 Å2, Q20 = 7 Å2. The Cs–N2 and Cs–H2 cross sections supersede the values published previously (McGillis and Krause 1967). The cross sections Q21 appear to exhibit resonances with molecular rotational transitions.
Widths and shifts of argon-II lines in a pulsed arc
Authors: Barnard A. J. , James H. G. , Neufeld C. R.
Published: April 2011

The spectrum of a high-density arc plasma was photographed with a 15 μs exposure time. The widths and shifts of 17 Ar-II lines were measured. While most lines have small blue shifts, the 4104 and 4278 Å lines have substantial red shifts. These two lines are also twice as wide as the other lines.
ESR spectrum of Fe+3 in topaz. II. Superhyperfine structure
Authors: Holuj F. , Quick S. M.
Published: April 2011

The superhyperfine structure (shfs) aspect of the ESR spectrum of Fe+3 impurity in topaz (Al2SiO4F2) has been investigated at X-band frequencies. The shfs tensors of the two inequivalent 19F nuclei have been determined. The experimental results were analyzed in the formalism of the effective spin. The isotropic contributions to shfs tensors were found to be (in 10−4 cm−1) 25.6 and 30.0 and the dipolar contribution, 6.8 and 5.9, with errors of ± 0.5 (see Table V). The calculations leading to these values assume considerable distortions at the Fe+3 site.
The admittance of an infinite cylindrical antenna in a lossy, compressible, anisotropic plasma
Authors: Miller Edmund K.
Published: April 2011

An analysis of the current on an infinite cylindrical dipole antenna which is excited across a circumferential gap of nonzero thickness and immersed in a lossy, compressible magnetoplasma with its axis parallel to the static magnetic field is described. Some numerical results are presented for the antenna admittance for the sheathless case, where the uniform magnetoplasma is in contact with the antenna surface. The admittance values are obtained from a numerical integration of the Fourier integral for the antenna current, and are given for plasma parameter values typical of the E region of the ionosphere.The admittance values obtained exhibit a maximum slightly above the electron cyclotron frequency, and in this regard are similar to the admittance when the magnetoplasma is incompressible but separated from the antenna by a free-space layer (the vacuum sheath). In addition, the admittance is found to have a slight minimum at the plasma frequency and to have a more pronounced minimum at the upper hybrid frequency where also the susceptance changes sign, these minima not being significantly affected by the plasma compressibility or vacuum sheath. These features of the calculated admittances are found to have a qualitative resemblance to experimental results obtained from antenna measurements in the ionosphere.
Superconductivity of very thin aluminium films
Authors: Walmsley D. G. , Campbell C. K. , Dynes R. C.
Published: April 2011

This note presents the results of superconductive tunneling measurements which show that very thin (50–100 Å) aluminium films exhibit a unique superconducting energy gap. The temperature dependence of this gap is BCS-like, and the ratio of the gap magnitude—as extrapolated to T = 0 °K (2Δ(0))—to the observed transition temperature, Tc, remains close to the usual BCS value of 3.52 k. The effect of crystallite size on deviations from BCS results is also discussed in relation to experimental observations.
Slater–Condon parameters evaluated from analytical Hartree–Fock functions
Authors: Fisk Carolyn , Fraga Serafin
Published: April 2011

The Slater–Condon integrals for the positive ions, neutral atoms, and negative ions from He to Ar have been evaluated from analytical Hartree–Fock functions.
Analysis of the 19F(p, α)16O reaction
Authors: Hird B. , Li T. Y.
Published: April 2011

An attempt is made to fit quantitatively the 19F(p, α)16O ground-state angular distribution at an energy where direct processes are likely to predominate. The nuclear structures of this reaction favor the direct pickup process. The finite range effects were shown to be large. No unique fit, or choice between ambiguous input parameters, was found to be possible using two forms of the local-energy finite range correction. The overall magnitude was in good agreement with the theoretical spectroscopic factor, as calculated from both LS and jj coupling wave functions.
The infinite cylindrical antenna in a compressible plasma
Authors: Nguyen D. T.
Published: April 2011

A theoretical model of an infinite cylindrical antenna, fed by a delta-function generator and immersed in a compressible, isotropic, lossless plasma, is considered in detail. A modal solution is found for the associated wave-guide problem inside the antenna; apart from the slow mode, the wave-guide modes are grouped into three sets: optical, acoustic, and hybrid modes. The current wave on the outside wall of the antenna is separated into its components: the familiar electromagnetic wave, the "transverse electro-acoustic" wave which is due to the axial oscillation of electrons near the gap, and the slow surface wave. These wave components have been calculated numerically using an IBM 1130 digital computer. It is found that the electromagnetic as well as the "transverse plasma" waves have a logarithmic singularity at the gap. It is also found that at a relatively large distance from this gap the first component decays as [Formula: see text], while the second component decays very rapidly to zero.
Infrared spectra, rotational correlation functions, and intermolecular mean squared torques in compressed gaseous methane
Authors: Armstrong R. L. , Blumenfeld S. M. , Gray C. G.
Published: April 2011

Extensive measurements of the methane ν3 and ν4 fundamental vibration–rotation bands in CH4–He mixtures and the ν3 band in CH4–He, CH4–N2, and CD4–He mixtures have been carried out in infrared absorption at 295 °K to pressures of 3000 atm. Some profiles of the ν3 band in CH4–Ar mixtures and in pure CH4 have also been obtained. Rotational correlation functions, band moments, and intermolecular mean squared torques have been determined from the ν3 band profiles. Theoretical calculations of the mean squared torque due to anisotropic multipolar, induction and dispersion interactions have been carried out. The theoretical and experimental torques are in order-of-magnitude agreement for the CH4–N2 and CH4–CH4 systems; for CH4–He, CD4–He, and CH4–Ar the theoretical values are two to three orders of magnitude too small to account for the experimental values, indicating that in these cases the dominant contribution to the torques is given by the anisotropic overlap forces.
A T5 spin–lattice relaxation rate for non-Kramers ions
Authors: Walker M. B.
Published: April 2011

It is shown theoretically that, for non-Kramers paramagnetic ions, the second-order Raman phonon process gives a spin–lattice relaxation rate varying as T5 at low temperatures. This new relaxation rate for non-Kramers ions is similar to the one discussed by Orbach and Blume for multilevel Kramers ions. An unusual feature of the second-order Raman process as applied to non-Kramers doublets is that terms in the spin–lattice interaction which are diagonal in the spin states enter in an essential way. The conditions under which the T5 relaxation process dominates other relaxation processes are discussed.
The energy derivative of an integral over the Fermi surface, and its application to Mott's formula for the diffusion thermoelectric power
Authors: Jan J.-P.
Published: April 2011

The integral of an arbitrary function of the wave vector, over a surface of constant energy, is considered, and its derivative with respect to energy is calculated, without any simplifying assumptions. The result is applied to the diffusion thermoelectric power of a metal.
Pressure-induced infrared absorption of the fundamental band of hydrogen in H2–Ne and H2–Kr mixtures at room temperature
Authors: Reddy S. Paddi , Lee W. F.
Published: April 2011

The pressure-induced infrared absorption of the fundamental band of hydrogen in H2–Ne and H2–Kr mixtures was studied at room temperature at a path length of 25.8 cm at pressures up to 400 atmospheres for different base pressures of hydrogen. In the enhancement absorption profiles of the band in H2–Ne mixtures, the S(1) line at all pressures and the QP component at low pressures show doublet structures. In the enhancement contours in H2–Kr mixtures, there is an indication of the QQ component between the QP and QR maxima at higher pressures, and the O and S lines are much stronger than the corresponding lines in H2–Ne mixtures. Integrated absorption coefficients were measured for each of the mixtures studied, and the binary and ternary absorption coefficients were derived. The values of the binary coefficients are 2.37 × 10−35 cm6 s−1 for H2–Ne and 7.56 × 10−35 cm6 s−1 for H2–Kr.
Study of levels in 24Mg
Authors: Ollerhead R. W. , Kuehner J. A. , Levesque R. J. A. , Blackmore E. W.
Published: April 2011

Nineteen levels in 24Mg have been studied utilizing the reaction 12C(16O, αγ)24Mg. Angular correlation measurements have established the spins and parities of levels at excitation energies of 7.35, 7.56, 7.62, 8.44, 8.65, 9.00, 9.15, and 10.1 MeV as 2+, 1−, 3−, 1−, 2+, 2+, 1−, and 0+ respectively. Levels at 8.12 and 13.18 MeV have been identified as the 6+ and 8+ members of the K = 0 ground-state rotational band; levels at 7.81 and 9.52 MeV have been identified as the 5+ and 6+ members of the K = 2 rotational band based on the 2+ level at 4.23 MeV. The existence of doublets has been established at excitation energies of 8.44 and 9.52 MeV; in each case, one member of the doublet is populated in the beta decay of 24Al, and the present experiment indicates that these two levels have spin and parity 4+. Assignments are also suggested for levels at 7.75 MeV (1+) and 8.36 MeV (2+). Gamma-ray spectra have been obtained for levels at 8.86, 9.28, and 9.46 MeV. The properties of levels assigned to rotational bands are compared to the predictions of the rotational model for an axially symmetric nucleus.
A computer calculation of Fermi surface cross sections using the empty lattice model
Authors: Taylor Roger
Published: April 2011

A computer program has been written in Fortran IV to calculate the areas of Fermi surface cross sections using the empty lattice model often referred to as the one-OPW model. The program employs the Harrison (1960) construction and will work for any structure with any Fermi radius. For hexagonal structures both the single and double zone schemes may be employed. Any plane may be selected by the user. This plane may be rotated a specified number of times about two axes and also shifted along one of the axes in order to search for extremal orbits along this axis. In applying the program to complicated Fermi surfaces a qualitative sketch of the surface may be necessary for the correct interpretation of the computer output. A copy of the deck of cards comprising the program may be obtained from the Depository of Unpublished Data.
An accurate method for determining the Q factor of a resonant cavity
Authors: Dagg I. R. , Mue A. M. , Reesor G. E.
Published: April 2011

A method for the very precise determination of the Q factor of a resonant cavity has been developed. It is based on careful standing-wave measurements taken on a slotted line in front of the cavity over a range of frequencies about the resonant frequency. It is necessary to choose and maintain the frequency to within one or two parts in 109 and to hold the average temperature of the cavity constant to better than 0.001 °C. A large number of readings are taken and the data are processed on an electronic computer. The method has been tested on a reflection-type cavity of rectangular cross section designed for operation in the X band. Reproducibility to within 0.1% has been achieved on successive determinations of Q.
The distribution of binding energy in a nucleus and fission
Authors: Kohut M. , Harvey M.
Published: April 2011

The concept of distribution of binding energy is considered for a "realistic" two-body potential and realistic kinetic energy with the 16O nucleus treated as an example. The relationship with the nuclear fission process is discussed.
On the form of the intracollisional dipole correlation function
Authors: Sears V. F.
Published: April 2011

Two apparently incompatible expressions for the intracollisional dipole correlation function, which have been proposed recently, are examined and found to be closely related and not inconsistent.
A contribution to the analysis of grain boundary diffusion measurements
Authors: Kučera Jaroslav
Published: April 2011

The Whipple and Suzuoka exact solutions of the grain boundary diffusion problem have been extended to the Gruzin method. The penetration curves for these two solutions were evaluated numerically using the method of penetration depth measurement, the sectioning method, and the Gruzin method. With the results obtained, relationships are given which make the evaluation of grain boundary diffusion coefficients in the low concentration range (up to 0.005%) comparatively easy. For all three experimental methods the Whipple and Suzuoka solutions have been compared. The comparison for the method of penetration depth measurement was only possible in the low concentration range. When evaluating the data in the low concentration range, using Whipple's or Suzuoka's solutions, approximately the same values of grain boundary coefficient are obtained, irrespective of the experimental method used. A comparison of the solutions using the sectioning and the Gruzin methods in the high concentration range (100%–0.1%) shows that the Gruzin method is not sensitive to the mathematical model used for treating the experimental data. The application of Whipple's solution to the data corresponding to Suzuoka's model gives higher values of the volume diffusion coefficient and slightly higher values of the grain boundary diffusion coefficient in the sectioning method and vice versa.
Perturbed angular correlations in 177Hf
Authors: Brooker W. H. , McMath T. A. , Murray J. , Cameron J. A.
Published: April 2011

Ions of 177Lu have been implanted in iron and nickel hosts at concentrations of about 1018/cm3. Perturbation of angular correlations in the gamma-ray cascade through the 113–keV level gives values for the internal fields on hafnium nuclei in these metals at room temperature and for this concentration of H(Fe) = −140 ± 10 kOe and H(Ni) = −60 ± 10 kOe. The rotation of the 250-keV level was also observed in the iron host. The nuclear g factor of this state is g = +0.26 ± 0.09.
Calculated neutron spectra from 9Be(α, n) sources
Authors: Zwan L. Van der
Published: April 2011

The neutron spectra from 9Be(α, n) sources are calculated for the α emitters 241Am, 210Po,and 239Pu. For a Pu–Be source, peaks are found at neutron energies of 0.75, 1.20, 2.10, 3.15, 4.95, 6.50, 7.75, and 9.65 MeV. Similar peak positions are found for sources made with 241Am and 210Po. The effect of the α-energy losses in the α-emitting material is studied by means of a simple model consisting of clusters of the α-emitting material embedded in a matrix of beryllium. For sources composed of clusters of AmBe13 or PuBe13 in beryllium, the changes in shape of the neutron spectrum are minor as the cluster size is increased from 0.5 to 20 μ. However, for sources consisting of clusters of Pu and Am or Po embedded in beryllium, the spectrum is considerably distorted as the cluster size is varied from 0.5 to 10 μ. The neutron yield per 106 α particles is calculated for sources having Am, Po, or Pu clusters ranging in size from 0 to 20 μ and AmBe13 or PuBe13 clusters ranging from 0 to 40 μ. The percentage of neutrons below 1.5 MeV including the contribution from the multiparticle reaction 9Be(α, αn)8 Be is estimated to be 16% for an AmBe13 type of source and 12% for a PuBe13 type of source, each with a cluster size of 0.5 μ.
Effect of a magnetic field on the banding phenomenon in aluminium–silicon eutectic alloy
Authors: Falquero E. A. , Saunders W. , Youdelis W. V.
Published: April 2011

The effect of a magnetic field on the frequency of transverse band formation in directionally solidified Al–Si eutectic alloy is investigated for a range of solidification speeds. The band spacing for both field and no-field ingots is found to be linearly dependent on the solidification rate, but for a given solidification speed a magnetic field of 30 000 Oe, applied perpendicular to the solidification direction, reduced the band spacing by approximately 35%. The results are explained in terms of the effects of the solidification rate and magnetic field on the impurity concentration ahead of the solid–liquid interface, a fluctuating impurity level being the direct cause of the banding phenomenon. It is shown that the magnetic-field effect on band spacing is consistent with the theories (previously published) developed to account for the observed effects of a magnetic field on alloy diffusion and solidification.
New spectrum of the SiO+ molecule
Authors: Nagaraj S. , Verma R. D.
Published: April 2011

A new spectrum of SiO+ in the region 4300–4100 Å has been obtained by a r-f. discharge through a flowing mixture of argon and SiCl4 which contained a trace of oxygen. This spectrum is mainly a long sequence Δν = 0. The rotational structure of the three bands 0–0, 1–1, and 2–2 has been analyzed and the rotational constants of the upper and lower states are determined.The known spectrum of SiO+ in the region around 3840 Å (Woods 1943) has also been obtained, with improved intensity under the above conditions and has been reanalyzed. It is found that the earlier numbering of the lines of this system is wrong by one unit and that the lower state of these bands and the upper state of the new bands represent the same state. The weak band, which was analyzed by Woods as 1–1, appears to fit as 2–2 according to the new analysis.Rotational constants of the three 2Σ states, which are named X, A, and B, are shown below (in cm−1):[Formula: see text]A discussion on electron configurations has also been included.
Assessment of the qualities of some electronic wave functions by a modified local-energy method
Authors: Rourke T. A. , Stewart E. T.
Published: April 2011

The validity and desirability of using different weighting factors with the modified local-energy method which was developed previously (Rourke and Stewart 1967) is indicated.The possible advantages of this method over the variation method are discussed and a search is made among the more common types of wave function for those which are of sufficiently high quality for use with this modified local-energy method. It is shown that the more common wave functions are unlikely to reach this standard except when electron–electron correlation effects are very low.A regression curve for the accuracy of energies by the present method and the accuracy by the variation method is given. It shows that the results from the variation method are always likely to be more accurate than those from the modified local-energy method when the same wave functions are used.Since one advantage of a local-energy method is the ease with which the type of wave function can be changed, a more systematic search for suitable wave functions by optimizing the analytical expression as well as variable parameters appears worthwhile.
On the variations of the mean recorded multiplicity in the super neutron monitor 9-NM-64 at Oulu, Finland, for the period November 5, 1965 to April 30, 1967
Authors: Niemi Sauli
Published: April 2011

An 18-month measurement of the mean recorded multiplicity [Formula: see text] in a cosmic-ray super neutron monitor 9-NM-64 has been performed. The main principles of the calculation of [Formula: see text] have been presented. The variations of the intensity recorded by the cosmic-ray neutron monitor are, percentage wise, found to be smaller with the multiplicity effect than without it. The time variations of the standard deviation correction factor [Formula: see text] seem to be negligible.
Gamma rays from the interaction of 14.1-MeV neutrons
Authors: Martin P. W. , Stewart D. T.
Published: April 2011

Gamma rays following the interaction of 14.1-MeV neutrons with natural samples of Na, Mg, S, Si, Mn, and Fe have been studied using an associated particle time-of-flight technique. The analysis has revealed several previously unreported gamma rays following neutron scattering and neutron-induced reactions. Assignments have been made for the possible reaction processes and transition modes.
Conduction band of InAs
Authors: Kwan Clarence C. Y. , Woolley John C.
Published: April 2011

Measurements of transverse magnetoresistance and Hall effect have been made at 4.2 °K on various In2Se3-doped and In2Te3-doped InAs polycrystalline specimens with magnetic fields up to 3.2 Wb/m2. An analysis of the results gives values of electron concentrations n0 and n1 and mobilities μ0 and μ1 for both the (000) and [Formula: see text] conduction-band minima. From the values of n0 and n1, the energy separation of the (000) and [Formula: see text] minima E01 of pure InAs has been determined to be 0.70 + 0.02 eV and is found to decrease with increasing impurity content, the rate of reduction being 0.13 ± 0.02 eV/at.% selenium and 0.17 ± 0.03 eV/at.% tellurium. Room-temperature measurements of electroreflectance and infrared absorption have also been made, and these indicate that the variation in E01 is due to the movement of the (000) conduction-band minimum relative to the valence band.
A reformulation of the dimer problem
Authors: Gibberd R. W.
Published: April 2011

It is shown that the partition function of the generalized dimer problem can be formulated in terms of a vacuum-to-vacuum expectation value of time-ordered operators. This expression is then evaluated by using Green's function technique, which has already been used in conjunction with the Ising model and ferroelectric problem.
The excited electronic states of the NO+ ion
Authors: Huber K. P.
Published: April 2011

The photoelectron spectrum of NO (Turner and May 1966) is given a new interpretation in terms of electronic states of NO+ belonging to configurations … (5σ)2(1π)32π and … 5σ(1π)42π. The close analogy with corresponding states of N2 and CO is pointed out. The long-known β Rydberg series of absorption bands of NO is shown to converge towards … 5σ(1π)42π, 3Π, but no evidence can be found for the existence of an electronic state of NO+ at the limit of the α series. The previously assumed Rydberg character of this series appears to be erroneous.
Perturbation theory and the local compressibility approximation in classical statistical mechanics
Authors: Smith W. R. , Henderson D. , Barker J. A.
Published: April 2011

The integrals which appear in the first-order term and the local compressibility approximation to the second-order term in the Barker–Henderson perturbation theory of fluids are evaluated analytically for the square-well potential in one and three dimensions and are compared with exact calculations.
A comparative study of ground-pressure waves in various atmospheric models
Authors: MacKinnon Robert F.
Published: April 2011

Dispersion curves and stationary phase contributions to theoretical ground-pressure waves from low-altitude nuclear explosions are presented for model atmospheres containing winds. Comparison is made with previously published results. It is shown that the reflection of waves above an altitude of 120 km can result in certain effects in waves with periods greater than 5 minutes. These effects are readily observable in microbarographic records associated with nuclear explosions. It is shown that winds can have a pronounced effect on wave characteristics at periods between 1 and 10 minutes. It is concluded that the effects of low-atmospheric winds are best observed in the behavior of waves of periods less than 4 minutes. Details are given of the numerical procedures followed in obtaining results.
Angular distributions of fast photoneutrons from thirteen elements,
Authors: Jury J. W. , Hewitt J. S. , McNeill K. G.
Published: April 2011

The angular distribution of fast (> 5 MeV) photoneutrons from V, Cr, Mn, Br, Mo, Ru, Rh, Pa, Sb, La, Pr, Pt, and Pb have been measured at bremsstrahlung energies of about 22 MeV. The results expand and confirm previously noted variations of anisotropy with neutron occupation number, and in particular they confirm the peaking of the anisotropy at the closing of p and d subshells.
Least-squares fitting of a straight line
Authors: Williamson J. H.
Published: April 2011

An efficient method is given for computing the best straight line by least squares when there are statistical errors in both coordinates. Exact expressions are obtained for the variances of the slope and intercept.
Elastic scattering of 4.56-MeV neutrons on lead from 10° to 40°
Authors: Tripard G. E. , Martin P. W. , White B. L.
Published: April 2011

The differential elastic scattering cross section for 4.56-MeV neutrons on natural lead was measured for angles at 5° intervals between 10 and 40°. The results were corrected for absorption and multiple scattering and are compared with other recent measurements using different techniques at similar neutron energies.
Multiple ionization of mercury by successive electron impacts
Authors: Redhead P. A. , Feser S.
Published: April 2011

Mercury ions of charge multiplicity up to n = 9 have been formed by repeated collisions of slow electrons (less than 150 eV) with ions trapped in an electron beam of high current density (~5 × 10−2 A cm−2). Ion current is observed at electron energies below the ionization potential for all multiply charged ions up to n = 8 and is ascribed to collision sequences involving metastable states of the ions (eN/eNm/ee(N + 1), where N represents an ion of charge multiplicity n). All the breaks observed in the ionization probability curves for [Formula: see text] can be explained in terms of collision sequences involving spectroscopically known metastable levels as limiting steps. Measured ionization potentials of the highly ionized species up to n = 9 are in reasonable agreement with extrapolation of spectroscopic values.
On the electric dipole moment of HD
Authors: Karl Gabriel
Published: April 2011

A formula is proposed to represent the J dependence of radial matrix elements of the electric dipole moment of HD.
The anisotropy of fast photoneutrons from chromium
Authors: McNeill K. G. , Hewitt J. S. , Jury J. W.
Published: April 2011

The anisotropy of fast (>5 MeV) photoneutrons from chromium and lead has been measured as a function of bremsstrahlung energy in the region 22–32 MeV. In the case of chromium the anisotropy increases with energy; a possible explanation for this is advanced, and the implications of this explanation are compared with results from other nuclei.
An investigation of hydrodynamic surface waves with a cylindrical microwave resonator. I. Theory of method
Authors: Curzon F. L. , Pike R. L.
Published: April 2011

In the first of this series of papers, we show that shifts in the resonant frequencies of a microwave resonator produced by boundary distortions can be used to study surface waves on conducting fluids.Surface waves can easily be studied under conditions where linearity requirements are satisfied. In addition, it is shown that a resonator of rectangular cross section acts as an analogue Fourier analyzer, so that a surface mode of a particular geometry can be observed, even when several modes are present simultaneously on the fluid surface. General results for a cylindrical resonator are first derived for TE and TM electromagnetic modes, and detailed calculations are then presented for resonators of rectangular and circular cross sections, since these are the most important practical examples.
Dicke narrowing and collisional broadening of the S0(0) and S0(1) Raman line of H2
Authors: Cooper V. G. , May A. D. , Hara E. H. , Knapp H. F. P.
Published: April 2011

The width of the rotational Raman lines of H2 was studied in the region of density from 1 to 100 amagats at room temperature. Collisional narrowing and collisional broadening of the lines is observed with a minimum in the width of the lines occurring near a density of 10 amagats. A comparison of the width of the S0(0) and S0(1) lines indicates that collisions which produce the broadening and the collisions which produce the narrowing are uncorrelated. The observations are only qualitatively in agreement with the theory of the width of the lines.
Study of the rotation–vibration band 2ν4 of CH3F
Authors: Anttila Rauno , Huhanantti Mikko
Published: April 2011

The perpendicular component of the 2ν4 band of CH3F around 6000 cm−1 has been investigated. Besides the Q branches, R and P lines have also been measured and assigned to subbands for [Formula: see text]. Using several combination plots and ground-state constants from previous investigations, molecular constants in the excited state have been derived. The following results, among other things, were obtained: B′ = 0.8560 ± 0.0004 cm−1, B′ – B″ = 0.0042 ± 0.0004 cm−1, A′ – A″ – (B′ – B″) = 0.048 ± 0.002 cm−1, and ζ44 = −0.170, which in turn gives ζ4 = 0.085 ± 0.001.
The D and D′ states of the PO molecule
Authors: Verma R. D. , Dixit M. N.
Published: April 2011

A rotational analysis of the 0–0, 0–1, and 0–2 bands of the D–B and D′–B systems of PO in the region 5500–6900 Å has been carried out from a spectrum obtained at a resolution higher than that of previous workers (Couet and Guenebaut 1966; Couet et al. 1967). The mutual perturbation between D2Πr and D′2Πr has been confirmed from the rotational analysis of the 0–0 and 0–1 bands of the D–A and D′–X systems in the region 2000–2200 Å. The analysis of the D′–X bands has shown that the previously reported E′ state lying between the D and D′ states is actually part of the D′ state. The constants of the D2Πr, D′ 2Πr, B2Σ+, and X2Π states are evaluated and compared with the constants of earlier workers to remove the inconsistency existing in their values for the B and X states.The isotopic bands corresponding to P18O of the D–B and D′–B systems are obtained, thus showing that the D′ state has an anomalous isotopic shift and that the observed levels of the D and D′ states have the vibrational quantum number ν =.
Free volume and significant structure theory applied to the viscosity of supercooled water
Authors: Gilra N. K.
Published: April 2011

The viscosity of supercooled water has been computed on the basis of free volume and significant structure theories. Excellent agreement has been found between the calculated and experimental results, which confirms the idea of Barlow, Lamb, and Matheson (1966). An excellent correlation has been shown between the free volume and the volume of unbonded liquid at 0 and 10 °C, better than that shown by Miller (1963).
Inelastic collisions between excited alkali atoms and molecules. V. Sensitized fluorescence in mixtures of sodium with N2, H2, HD, and D2
Authors: Stupavsky M. , Krause L.
Published: April 2011

3 2P1/2 ↔ 3 2P3/2 excitation transfer in sodium, induced in inelastic collisions with ground-state N2, H2, HD, and D2 molecules, has been investigated in a series of sensitized fluorescence experiments. Mixtures of sodium vapor at a pressure of 5 × 10−7 Torr, and the gases, were irradiated with each NaD component in turn, and the fluorescence which contained both D components was monitored at right angles to the direction of the exciting beam. Measurements of the relative intensities of the NaD fluorescent components yielded the following collision cross sections for excitation transfer. For Na–N2 collisions: Q12(2P1/2 → P3/2) = 144 Å2, Q21(2P1,2 ← 2P3/2) = 76 Å2 for Na–H2 collisions: Q12 = 80 Å2, Q21 = 42 Å2. For Na–HD collisions: Q12 = 84 Å2, Q21 = 44 Å2. For Na–D2 collisions: Q12 = 98 Å2, Q21 = 52 Å2. The cross sections Q21 exhibit a slight resonance effect between the atomic and molecular rotational transitions.