bluuebunny/crossref_metadata_2025 huggingface dataset:
Gigawatt peak-power pulse generation by injection of a single short pulse in a regenerative amplifier above threshold (RAAT)
Authors: Bélanger Pierre-André , Boivin Jacques
Published: April 2011

We propose a very simple technique to extract, in a short pulse with good optical quality, all the laser energy in a pulsed system. The method essentially consists of injecting into a high power laser a short and weak pulse at a moment close to the time when the gain is equal to the losses (laser threshold). Subsequently, the spontaneous emission radiation is dominated at all times by the injected pulse. After multipass amplification, all the energy available in the system is extracted by the injected pulse.In this way, pulses of 2 ns have been obtained from a TEA–CO2 laser of 15 J.
Analyse rotationnelle d'un système vert 2Πi–X2Πi de la molécule CuO
Authors: Lefebvre Y. , Pinchemel B. , Bacis R.
Published: April 2011

Spectra of CuO at a very low rotational temperature have been obtained from a 'composite wall' hollow cathode in the 5200–5500 Å region.The rotational analysis of two bands has shown that this system comes from a transition between a new 2Πi state and the X2Πi ground state.The constants derived for the new 2Πi, state are (in cm−1)[Formula: see text]
Disorientation of Cs(62P1/2) atoms, induced in collisions with noble gases
Authors: Niewitecka B. , Krause L.
Published: April 2011

The disorientation of 62P1/2 cesium atoms, induced in collisions with noble gas atoms in their ground states, was systematically investigated by monitoring the depolarization of cesium resonance fluorescence in relation to noble gas pressures. The Cs atoms, contained together with a buffer gas in a fluorescence cell and located in zero magnetic field, were excited and oriented by irradiation with circularly polarized 8943 Å resonance radiation, and the resonance fluorescence, emitted in an approximately backward direction, was analyzed with respect to circular polarization. The experiments yielded the following disorientation cross sections which have been corrected for the effects of nuclear spin: Cs–He: 4.9 ± 0.7 Å2; Cs–Ne: 2.1 ± 0.3 Å2; Cs–Ar: 5.6 ± 0.8 Å2; Cs–Kr: 5.8 ± 0.9 Å2; Cs–Xe: 6.3 ± 0.9 Å2. The results are in good agreement with most of the available zero-field and low-field data.
Cross section measurements for the reactions of fast neutrons with indium
Authors: Santry D. C. , Butler J. P.
Published: April 2011

Excitation curves for the reactions 115In(n,n′) 115Inm, 113In(n,n′)113Inm, and 115In(n,2n)114Inm have been measured by the activation method. The neutron flux at energies below 5.1 MeV was determined with a calibrated neutron long counter while at higher energies, measurements were made relative to the known cross section for the 32S(n,p) reaction. Effective cross sections for a 235U fission-neutron spectrum calculated from our measured excitation curves are 173 ± 9 mb for 115In(n,n′)115Inm, 123 ± 24 mb for 113In(n,n′)113Inm, and 0.64 ± 0.06 mb for 115In(n,2n)114Inm.
A temperature-dependent self-consistent calculation of localized-spin–fluctuation effects in AlMn
Authors: Cheung C.Y.
Published: April 2011

The renormalized local-spin–fluctuation theory of Paton and Zuckermann is extended in a temperature-dependent calculation. It is found that the temperature dependence of the renormalization parameters produce significant quantitative effect in the linear-T region of the effective density of d states.
The Wiener–Hopf–Hilbert method for diffraction problems
Authors: Hurd R. A.
Published: April 2011

A powerful method of solving diffraction problems is described. In it, a system of Wiener–Hopf equations is transformed into a system of Hilbert problems. The latter apparently can be solved fora wider range of problems than the former. As an example, the diffraction problem of a plane wave incident on a half-plane with different face impedances is considered. This problem is not solvable by ordinary Wiener–Hopf techniques, but yields to the new method. Possible applications to some unsolved problems are mentioned.
Measurement of the scattering of an electromagnetic wave from an electron beam
Authors: Hodjat F. , Seeger J. A.
Published: April 2011

A uniform plane wave incident on a cylindrical electron beam is simulated using a wave guiding structure consisting of parallel planar conductors. The wave guide is fed with a horn antenna using a pulse generator providing 4 kW peak power at 1.080 GHz. Scattered field from the electron beam is measured by a probe using a cancellation technique. Measurements compare favorably with theory.
A comparison of the optical properties of crystalline and amorphous CdS
Authors: Wohlgemuth J. H. , Brodie D. E. , Eastman P. C.
Published: April 2011

Polycrystalline and amorphous films of CdS have been vacuum deposited onto fused sapphire substrates. The polycrystalline samples are obtained using heated substrates and the amorphous samples are grown on cooled substrates. The material is considered to be amorphous if the crystallite size is smaller than 20 Å as determined by X-ray diffraction.Normal incidence reflection and transmission have been measured by the sample-in, sample-out technique over a range of wavelengths (2600 Å < λ < 9000 Å) for both polycrystalline and amorphous materials. The complex index of refraction has been calculated using a smooth curve thickness variation method developed by the authors. The polycrystalline results agree well with previous values except in the ultraviolet portion of the spectrum. In this region, the crystalline films exhibit surface roughness due to the crystallite grains and hence cause the measured reflectivity and calculated index of refraction to be smaller than the bulk values. The amorphous material does not show this decrease at high energies because the grain size is much smaller. In the amorphous material the absorption edge is shifted to lower energies and is no longer a direct transition as in the crystalline case, but is a nondirect transition. The optical data are consistent with a model of an amorphous material which assumes that, at low photon energies, transitions take place from localized to extended states (or vice-versa) while at higher energies they also occur between extended states.
Lifetimes of some triplet levels of neutral strontium
Authors: Kelly F. M. , Mathur M. S.
Published: April 2011

The zero-field level-crossing technique has been used to determine the lifetimes of the 5p2 3P2,1 and 4d2 3P levels of neutral strontium. The results are compared with those given in the literature and calculated from the available values of oscillator strengths. We have determined the following lifetimes: τ(5p2 3P2) = 6.39 ± 0.20 ns; τ(5p2 3P1) = 6.91 ± 0.20 ns; τ(4d2 3P) = 6.74 ± 0.15 ns.
Détermination théorique et expérimentale des forces d'oscillateur des transitions de l'atome de césium
Authors: Fabry M. , Cussenot J. R.
Published: April 2011

A theoretical determination of oscillator strengths for the cesium atom is proposed. The values obtained are compared with experimental results deduced from the emission spectra of a slightly ionized quiescent cesium plasma discharge.
Rotational analysis of the violet electronic emission spectrum of titanium nitride
Authors: Bates J. K. , Ranieri N. L. , Dunn T. M.
Published: April 2011

A new electronic emission system of TiN has been observed in the violet region of the spectrum. It is the pure precession companion state B2Σ, of the previously known red A2Π → X2Σ system. Rotational analysis yielded the constants B0′ = 0.5745 cm−1, D0′ = 6.4 × 10−7 cm−1, and T0 = 23 487 cm−1.
Frequency shift and precession of elliptically polarized electromagnetic waves in a plasma
Authors: Lai C. S. , Wonnacott E.
Published: April 2011

The nonlinear propagation of an elliptically polarized electromagnetic wave in a neutral cold plasma in the long wavelength is studied. Our method of calculation for the frequency shift and precession of polarization axes is presented in the framework of classical mechanics. Our results appear valid for oscillations of arbitrary amplitude up to β < 0.7.
Collective motions in nuclei and the spectrum generating algebras T5 × SO(3), GL(3,R), and CM(3)
Authors: Gulshani P. , Rowe D. J.
Published: April 2011

Cusson's classical treatment of the collective rotations of a discrete system of N particles is extended to the full quantum mechanical system by means of a straightforward generalization of Villars' canonical transformation. In this manner, Bohr's collective Hamiltonian, with various values for the rotational mass, is microscopically derived. The nature and criteria for the existence of various collective flows in a many-body system are also given. The collective parts of the Hamiltonian are then separately expressed in original particle coordinates and momenta and in this manner the possibility of microscopic calculations for the collective motions is suggested. Finally appropriate microscopic Hamiltonians for the S.G.A.'s T5 × SO(3), GL(3,R), and CM(3) are determined.
Rapidity dispersion analysis of individual events in proton–nucleus interactions at 70 GeV
Authors: Daftari I. K. , Roy T.
Published: April 2011

An analysis of the dispersion parameter of the rapidity spectrum of particles in individual events in 70 GeV proton–nucleus interactions has been considered. Application of such a method of analysis of the interactions in photographic emulsions permits us to identify the clusters produced in such reactions.
Fluorine mean-life measurements below 1000 Å using the beam–foil technique
Authors: Pinnington E. H. , Irwin D. J. G. , Livingston A. E. , Kernahan J. A.
Published: April 2011

We have used the beam–foil technique to measure mean lives for 16 transitions in F I–F IV in the wavelength region 400 Å–1000 Å. Good agreement is found with the results of recent calculations, particularly those employing correlated wave functions. The f-value trends for 5 isoelectronic sequences are presented in detail (2p5 2P0–2p43s2 D and 2p5 2P0–2p43s 2P in F I; 2p4 3P–2p33s 3D0 in F II; 2p3 2D0–2s2p4 2D and 2p3 4S0–2s2p4 4P in F III). Our f value for the 955 Å multiplet in F I is also used in conjunction with some new satellite data to show that the fluorine abundance is apparently depleted in interstellar clouds by a factor of at least 3 below its solar value.
Rotational analysis of emission bands of the A2Πi–X2Πi system of 35ClO
Authors: Coxon J. A. , Jones W. E. , Skolnik E. G.
Published: April 2011

Five bands of the 0–ν″ progression (5 ≤ ν″ ≤ 9) of the A2Πi–X2Πi system of 35ClO have been rotationally analysed. The results have been combined with data from the absorption spectrum of ClO, and new molecular constants are reported. The variation of spin–orbit coupling with internuclear separation has been determined for both states.
High-field spin–lattice relaxation of cobalt nuclear spins in iron determined by nuclear orientation
Authors: Kieser R. , Turrell B. G.
Published: April 2011

In order to resolve the discrepancy in the various estimates of the spin–lattice relaxation rate for cobalt spins in iron, we have remeasured the relaxation time for 60Co spins using both magnetic resonance on the oriented spin system and a non-resonant method in which the lattice temperature is changed rapidly by fast demagnetization. The latter technique yields a value for the relaxation rate (γN2T1T)−1 = (0.43 ± 0.01) × 10−7 s G2 K−1 in an applied field of 3.2 kOe. Based on experimental results and theory, a proposal is made that there exists a field-dependent contribution to the relaxation rate even in the magnetically saturated state. Agreement is then found with NMR measurements on 59Co in iron. The resonant nuclear orientation experiment gives a result which is in doubt because of lack of knowledge of the initial conditions produced after the resonant destruction of the γ-ray anisotropy.
Changement de phase dans un champ de gravitation: Possibilité de détection interférentielle
Authors: Linet B. , Tourrenc P.
Published: April 2011

We calculate the phase shift of a quantum mechanics wave function and of an electromagnetic wave produced by any gravitational disturbance using the eikonal approximation. We examine the best conditions for detection of gravitational waves. In particular, we establish that any resonant effect has a linear time dependance.
The 2491 Å band system of NO2. Rotational structure and evidence for predissociation in the zero-point level
Authors: Hallin K. -E. J. , Merer A. J.
Published: April 2011

A detailed rotational analysis of the (0, 0) band of the [Formula: see text] electronic transition of NO2, at 2491 Å, has been carried out. Although the lines are slightly broadened as a result of predissociation, it has been possible to determine the five quartic centrifugal distortion constants and the spin–rotation coupling constant εaa for the upper state. The centrifugal distortion constants allow the position of the unseen vibrational level ν3′ to be estimated: the results offer no support to the suggestion of Coon, Cesani, and Huberman that there is a double minimum potential function in the antisymmetric stretching coordinate of the 2B2 state. The geometric structure of the zero-point level of the 2B2 state is r(N—O) = 1.3142 Å, [Formula: see text], and its lifetime (as calculated from the linewidths) is 42 ± 5 ps.
Photoneutrons from 19F
Authors: Sherman N. K. , Lokan K. H. , Gellie R. W.
Published: April 2011

The 19F(γ,n) reaction was studied by irradiating teflon with bremsstrahlung of energy increasing from 13 MeV to 21 MeV in 1 MeV steps. Photoneutron spectra were measured by the time-of-flight method. Excited states of 19F at 12.10, 12.38, 13.82, and 16.24 MeV were observed. The total integrated cross section between 11.9 and 17.9 MeV was found to be (14.4 ± 2.2) MeV mb. Branching ratios to the first group of excited states of 18F compared to the ground state were measured, along with resonance widths and approximate radiative widths. They are consistent with the interpretation that all four states arise from electric dipole d → f valence transitions, with the first two states having Jπ = 1/2−, and the second two having 3/2−.
Zero-field splitting calculations. Part I. Evaluation of possible perturbation mechanisms for the Mn2+ ion in an axial crystalline electric field
Authors: Chatterjee R. , Smith M. R. , Buckmaster H. A.
Published: April 2011

The contributions to the zero-field splitting parameter D for an axial crystalline electric field for Mn2+ (site I) in La2Mg3(NO3)12∙24H2O have been calculated from the known and new perturbation mechanisms up to and including fourth order, using the relativistic wave functions. It is shown that the largest contribution to the observed value of D is due to the second-order perturbation mechanism, in agreement with the prediction of van Heuvelen.
Zero-field splitting calculations. Part II. Tabulation of the reduced matrix elements of the irreducible double tensor operators
Authors: Chatterjee R. , Smith M. R. , Buckmaster H. A.
Published: April 2011

The many-electron reduced matrix elements of the double tensor operator [Formula: see text] are tabulated for the pn, dn and fn configurations. These tables have been calculated from the Racah formalism and form an extension of the tabulations given by Nielson and Koster for K2 = 1. The relationship of this tensor with the other double tensors and the calculation of the matrix elements is summarized. See Chatterjee et al for an application.
Ultra cold neutrons from a polyethylene converter
Authors: Robson J. M.
Published: April 2011

Ultra cold neutrons from a polyethylene converter located in the thermal column of the NRU reactor have been transmitted along a highly polished copper tube of length 5.3 m. The measured intensity and its variation with gas pressure in the tube indicate that the reflections are almost 100% specular. The yield of the ultra cold neutrons increases by a factor of 3 as the polyethylene is cooled from 40 °C to −170 °C.
Loci of maxima and minima of thermodynamic functions of a simple fluid
Authors: Stephenson John
Published: April 2011

Some elementary properties of loci of extrema of thermodynamic functions are established and discussed in connection with maxima and minima of the constant volume specific heat, CV, the isothermal compressibility, χT, and the constant pressure specific heat, CP, along isotherms, and the extremum properties of the isobaric coefficient of expansion, αP, along isobars. Experimental results for fluid argon are used to construct the required loci of extrema. Van der Waals' equation is applied to obtain loci of extrema for χT, CP, and αP, for the speed of sound W, and for related inflexion loci.
'Straightening through smoothings' seen as a digital filter
Authors: Marchand P. , Veillette P.
Published: April 2011

It is shown that the digital signal processing method called 'straightening through smoothings' is exactly equivalent to a digital filter, even including end-effect corrections.
Etude du système A–X de PD2
Authors: Vervloet M. , Berthou J. M.
Published: April 2011

The rotational analysis of the ν′2 ← 0 bands of the A–X system of PD2 has been done for ν′2 = 1 to 10. The set of the 1034 difference combinations has permitted us to determine with good precision the rotational constants of the ν″2 = 0 level of the ground state. A comparison with the corresponding constants of PH2 has shown that the application of isotopic relations to the rotational constants leads to a very good approximation in the prevision of these constants.The excited state levels are marked by large amplitudes and the Renner effect. The BDD model already applied to PH2 fits very well with the PD2 experimental data. On the other hand, although localized perturbations are less numerous in the PD2 spectrum, the presence of some intense non-identified lines suggests that interactions between higher levels of the X(2B1) state and the first levels of the A(2A1) state are to be expected.[Journal translation]
A comparison of the chlorine nuclear relaxation in the dense paramagnetic insulators K2IrCl6 and K2ReCl6
Authors: Driel Henry M. Van , Armstrong Robin L.
Published: April 2011

Chlorine spin–lattice (T1) and spin–spin (T2) relaxation times as measured in the dense paramagnetic insulators K2IrCl6 and K2ReCl6 are tabulated. The Moriya theory of nuclear spin relaxation in magnetic insulators is extended to the case where the nuclear quadrupole interaction gives rise to the stationary eigenstates. Explicit expressions for T1 and T2 are derived in terms of the magnetic hyperfine interaction parameters A and B. The theory is tested by a comparison of the parameters deduced from the relaxation data with parameters obtained from spectroscopic experiments. For K2IrCl6, a comparison with recent ENDOR results confirms the general validity of the theory. For K2ReCl6, the only other results available are from an NMR experiment and the overall agreement is even qualitatively unacceptable. However, both experiments do suggest that [Formula: see text] is anomalously large.
The electron capture to positron branching ratio in the decay of 22Na
Authors: MacMahon T. D. , Baerg A. P.
Published: April 2011

A new measurement has been made of the electron capture to positron branching ratio (e/β+) in the decay of 22Na to the 1.27 MeV level in 22Ne. The measurement was made using 4πβ–γ coincidence counting with a pressurized 4π-proportional β-detector and efficiency variation techniques. The value of 0.1077 ± 0.0006 obtained for the e/β+ ratio is about 3% larger than other precise values and is compared with recent theoretical estimates.
Theory of ultrasonic attenuation in one and two dimensional metals
Authors: Tiedje T. , Haering R. R.
Published: April 2011

The theory of ultrasonic attenuation in metals is extended so that it applies to quasi one and two dimensional electronic systems. It is shown that the attenuation in such systems differs significantly from the well-known results for three dimensional systems. The difference is particularly marked for one dimensional systems, for which the attenuation is shown to be strongly temperature dependent.
Calculation of the isothermal susceptibility by the Kubo formula
Authors: Morita T. , Horiguchi T.
Published: April 2011

The relation between the zero frequency limit of the frequency-dependent susceptibility and the isothermal susceptibility is made clearer by expressing them in terms of the spectral density function. The general formulas are illustrated for the perpendicular susceptibilities of the Ising model.
Analysis of the 3Φ → 3Δ, 1Δ → 1Π, and 1Σ → 1Π systems of lanthanum hydride, LaH and LaD
Authors: Bernard A. , Bacis R.
Published: April 2011

Three new electronic band systems, assigned to LaH, have been observed both in emission (by means of a composite wall hollow cathode) and absorption (in a King furnace). The similar systems of LaD have been observed in emission. They appear between 5300 and 6500 Å. Rotational analyses of the bands have made it possible to identify the corresponding transitions as 3Φ → 3Δ, 1Δ → 1Π, and 1Σ → 1Π The singlet transitions have a common lower 1Π state. A rotational analysis of the (0, 0) and (1, 1) bands of the 3Φ4,3 → 3Δ3,2 sub-systems and of the (0, 0) band of singlet systems (with the exception of the 1Σ → 1Π system of LaD) is presented in this paper.
Effect of Fermi surface anisotropy on the thermodynamics of superconducting Al
Authors: Baquero R. , Carbotte J. P.
Published: April 2011

We have computed the effect of Fermi surface anisotropy on the low temperature specific heat and the nuclear spin–lattice relaxation in superconducting Al. It is found to be much more important in the first case than in the second.
Order fluctuations in p-methoxybenzylidene p-n-butylaniline (MBBA): A proton NMR study
Authors: Dong Ronald Y. , Tomchuk E. , Visintainer J. J. , Bock E.
Published: April 2011

Proton spin–lattice relaxation has been studied in the nematic phase of MBBA and MBBA-d8 samples. The proton T1 temperature dependence appears to come from the motions of side chains as in p-azoxyanisole. Order of magnitude calculations of T1 based on order fluctuations agree with the ring proton T1. The proton T1 frequency dispersion of MBBA at 18 °C can be explained by order fluctuations plus a frequency dependent B term without any cutoff in the hydrodynamic modes.
The Fröhlich Hamiltonian: mathematical results. I. Hamiltonian with cut-off
Authors: Dormale Bernard M. de , Bader Georges
Published: April 2011

We study the Fröhlich Hamiltonian with cut-off. We show that this Hamiltonian is self-adjoint in the Fock space and semibounded when the number of electrons is kept constant. The lower bound we give generalizes the bound obtained for one electron by Lee and Pines to the case of several electrons. We also give a domain where the perturbation series for the resolvent of the Hamiltonian does converge in the operator norm. Finally, we study the influence of the Coulomb interaction.
Optical and electrical properties of ammonium perchlorate doped with chromate ions
Authors: Hor Ah Mee , Radhakrishna S. , Jacobs P. W. M.
Published: April 2011

The presence of CrO42− ions incorporated substitutionally in single crystals of NH4ClO4 grown from saturated solutions containing 0.1 mol% or 1 mol% CrO42− ion has been demonstrated by measurements of optical absorption, Raman scattering, dielectric loss, and ionic thermoconductivity. The three latter experiments also show the presence of dipoles associated with the CrO42− ions. The dc conductivity of NH4ClO4 crystals is enhanced by doping with CrO42− so that charge transport by defects introduced by the CrO42− ions is inferred. The implications of this finding with respect to mechanisms of charge transport in ammonium perchlorate are discussed.
Two-phonon absorption in InSb, InAs, and GaAs
Authors: Koteles E. S. , Datars W. R.
Published: April 2011

Far-infrared absorption in the III–V compound semiconductors InSb, InAs, and GaAs has been measured using a Fourier transform spectrometer. The high-resolution spectra of the three materials were found to be very similar. Features on the spectra were assigned to two-phonon sum and difference processes with the aid of two-phonon density-of-states curves for InSb and GaAs calculated from a shell model fit to phonon dispersion curves. Interpretation of the spectrum of InAs was possible because of its similarity to that of InSb and GaAs. The frequencies of phonons at certain points in the Brillouin zone of InSb and GaAs determined from the mode assignments to the infrared spectra were in good agreement with previous measurements by inelastic neutron scattering and Raman scattering.
Groupe de dégénérescence de l'Hamiltonien de vibration–rotation des molécules toupies sphériques. Application à l'étude des moments de transition
Authors: Hilico Jean-Claude , Berger Hubert , Loete Michel
Published: April 2011

Symmetry properties, widely used for theoretical study of molecular energy levels or transition probabilities, are generally referred to the only invariance group of the molecule which is a group of isometrics in the frame of reference fixed with respect to the molecule. However, operators and wave functions of the purely rotational problem, and the transition operators have also symmetry properties related to the isometries of the laboratory frame of reference. We propose to take all those properties into account by introducing the molecular degeneracy group G × (F)O(3), where G is the invariance group of the molecular field and (F)O(3) is the group of rotations in the fixed frame of reference. In the case of spherical top molecules, the invariance group G of the molecular field can be extended, in a first approximation, to the complete rotation group (m)O(3), leading to the utilization of the chain [Formula: see text]. Using tensor techniques, we give general formulas for the calculation of transition moments for electrical dipole absorption processes (rotation–vibration and pure rotation) and Raman scattering.[Journal translation]
Analysis of heat transfer between solids at low temperatures
Authors: Cheeke J. D. N. , Ettinger H. , Hebral B.
Published: April 2011

A detailed analysis is given of the acoustic mismatch formulation first given by Little for the thermal contact resistance between solids for the case of phonon transport in a Debye model. Extrema in the heat transfer coefficients as a function of the refractive index of the interface are shown to be due to either impedance matching conditions or to the presence of the critical cone. Detailed numerical tables are presented which permit rapid evaluation of the heat transfer coefficient to an accuracy of 5% or better.
Diffraction ring pattern at the focal plane of a spherical lens – axicon doublet
Authors: Bélanger Pierre-André , Rioux Marc
Published: April 2011

A spherical lens and an axicon are combined to form an optical system producing a ring-shaped focalization pattern. The diameter of the ring in the focal plane depends on the angle of the axicon, on its dielectric index, and on the focal length of the spherical lens. The diffractional analysis of the lens–axicon combination, when illuminated by a plane wave, is presented. In particular, we show that, when the aperture is large, the Kirchhoff–Fresnel integral can be reduced to a known function. A close examination of the function reveals that the diffractional width of the ring is equal to approximately twice the width of the Airy pattern of the lens alone. This type of focalization is well suited for a system where a laser beam is used to drill holes.
The ground state g tensors of LiUF6, NaUF6, and CsUF6
Authors: Leung A. F.
Published: April 2011

The optical and magnetic properties of the 5f unpaired electron in LiUF6, NaUF6, and CsUF6 have been calculated using the electrostatic charge model. The g tensors of the ground state of these compounds show good agreement with experimental measurements.
The absorption spectrum of NH2 between 6250 and 9500 Å
Authors: Johns J. W. C. , Ramsay D. A. , Ross S. C.
Published: April 2011

The earlier analysis by Dressier and Ramsay of the [Formula: see text] absorption system of NH2 has been considerably extended at the long wavelength end of the spectrum. All the low-lying vibronic levels of the excited state have been identified up to ν2′ = 8. These levels are 010(K = 0), 020(K = 1), 030(K = 0,2), 040(K = 1,3), 050(K = 0,2,4), 060(K = 1,3,5), 070(K = 0,2,4,6), and 080(K = 1,3,5,7). Large perturbations (~ 200 cm−1) have been observed between some of these levels and high vibrational levels of the ground state. Accurate molecular constants have been obtained for the ground state and for the first level involving the bending vibration (ν2″ = 1).
Laser-induced breakdown in the rare gases using picosecond Nd:glass laser pulses: Theoretical interpretation through the effective-photon concept
Authors: Panarella E.
Published: April 2011

Breakdown thresholds in the rare gases irradiated with picosecond Nd: glass laser pulses have been measured recently as a function of gas pressure. The analysis has shown that the experimental results cannot be interpreted through the usual process of multiphoton ionization. The present paper demonstrates that these results are predicted by effective-photon theory and a correlation between gas ionization with nanosecond pulses and with picosecond pulses is shown to exist.
Lattice vibrations in tungsten at 22 °C studied by neutron scattering
Authors: Larose A. , Brockhouse B. N.
Published: April 2011

The phonon spectrum of tungsten at 22 °C has been reexamined along major symmetry directions using triple-axis neutron spectrometry. The purposes of the experiment were to search for a predicted Kohn effect near the H-point and to extend the previously published measurements. The results are in agreement with those already published, but the expected Kohn effect could not be unambiguously observed with the instrumental resolution available.
Monochromateur de vitesse pour macroions
Authors: Paquin Réal , Baril Marcel
Published: April 2011

We propose the use of a dynamic monochromator to reduce the energy spread of a macroion source. It is shown that the energy aberration can be corrected using linear acceleration after the particles are separated in a field free drift tube. We give a general expression for the resolution of the monochromator. We verify experimentally that the energy distribution of a beam of cesium ions of 160 eV mean energy could be reduced from 20 eV to 4.5 eV, giving an improvement of 4.3. with this monochromator which has an efficiency of 6%. Two suggestions to improve the transmission of the monochromator are also given.[Journal translation]
The B′2Σ+ → X2Σ+ systems of MgH and MgD
Authors: Balfour Walter J. , Cartwright Hugh M.
Published: April 2011

The B′2Σ+ → X2Σ+ systems in MgH and MgD have been studied in emission at high resolution. Vibrational and rotational analyses, which have been performed for 37 bands of MgH and 16 bands of MgD, provide data on the following vibrational levels of the B′ state: MgH, ν = 0–9; MgD, ν = 0–2, 4–6. The following molecular constants (in cm−1) have been determined for the B′ state: MgH, Tc = 22 410, ωc = 828.4, ωcxc = 11.8, Bc = 2.585, Dc = 1.2 × 10−4; MgD, Tc = 22 415, ωc = 598.1, ωcxc = 6.4, Bc = 1.346, Dc = 2.6 × 10−5. The dissociation energy, Dc, in the B′ state is estimated to be 10 900 cm−1 (MgH), 11 200 cm−1 (MgD). The RKR potential energy curve for the B′ state has been calculated. A correlation of the rotational perturbations in the B′ → X system with the positions of rotational energy levels in the A2Π and B′2Σ+ states has been made. Observations for the low-lying states of MgH are compared with similar available data for related hydrides.
A possible example of the alternative decay mode of 8He observed in nuclear emulsion
Authors: Deka G. C. , Pathak K. , Laskar I.
Published: April 2011

While studying the heavy fragments (Z ≥ 4) emitted from the disintegrations of silver and bromine nuclei by 5GeV/c antiprotons in nuclear emulsion, an event was found to have the decay characteristics of 8He in its rare decay mode, [Formula: see text].
Excitation of Ne VIII by electron impact
Authors: van Wyngaarden W. L. , Henry Ronald J. W.
Published: April 2011

Collision strengths for electron impact excitation of Ne VIII are calculated at 14, 18, and 30 Ry in a 5-state close coupling expansion and the unitarized Coulomb–Born approximation. To assess the importance of exchange and coupling beyond the 5 states, additional calculations are made at 18 Ry in 5-state and 8-state close coupling expansions without exchange. For the 2s–2p excitation, calculations below the 3s threshold at 10.0 Ry are made in a 2-state close coupling expansion at 1.6, 3.2, and 8.0 Ry. In most instances the close coupling method gives results which differ by 15% or less from those of the unitarized Coulomb–Born approximation and by 20–70% from the CBI (Coulomb–Born) results of Bely. Rate coefficients which are calculated from the results obtained in the close coupling approximation agree within experimental error with the experimental results of Kunze and Johnston and Haddad and McWhirter with the exception of the rate coefficient for the 2p → 3d excitation.
Electronic spectrum of H2O+
Authors: Lew H.
Published: April 2011

Many bands of the [Formula: see text] electronic emission spectrum of H2O+, occurring in the wavelength region 4000–7500 Å, have been analyzed. These include bands that have been observed in the tails of comets. The wavelengths and wave numbers of all assigned lines are tabulated. Accurate rotational constants for the first three bending vibrational levels of the ground state are given, as well as energy levels in the upper and lower electronic states. The O—H bond distance and the H—O—H angle in the [Formula: see text] (0, 0, 0) level are found to be 0.9988 Å and 110.46° respectively. Some predicted microwave and infrared lines that may be of astrophysical interest are included.
Hot electron in a polar crystal. I. The eikonal approximation
Authors: Hede B. , McMullen T.
Published: April 2011

A quantum theory of the rates of momentum and energy loss by a fast electron to the optic modes of a polar crystal as a function of time elapsed since injection of the fast electron is developed. A nonequilibrium Green function technique is used to formulate the problem, and permits inclusion of quantum interference between the individual phonon processes. An approximation, which has been called the eikonal approximation in high energy scattering and is valid when the fractional electron energy loss in a single phonon collision is small, enables us to sum the resulting diagrams. The relationship of this method to a Boltzmann equation approach is discussed.
Analyse rotationnelle et spectromètrique de la bande (2, 0) du système A2Π–X2Σ+ du radical CO+: Dédoublement Λ de l'état 2Π
Authors: Gagnaire H. , Goure J. P.
Published: April 2011

A high resolution grating spectrometer and a hollow cathode lamp were used to study the (2,0) band of the.A2Π–X2Σ transitions of the ion CO+. High resolution measurements permit satisfactory separation of the doublet components and facilitate study of the intensities, so it is possible to evaluate the p and q constants for the Λ splitting of the 2Π state. Earl's formulae are obeyed with a precision of better than 5%.
Change in the lattice energy of a polar crystal due to an impurity atom
Authors: Johri Gautam , Paranjape V. V.
Published: April 2011

The frequency shifts of the optical vibrations of a crystal due to the presence of a polarizable impurity atom are calculated by using a semiclassical approach. The temperature dependent energy of a bound polaron is described in terms of these frequency shifts. The impurity lattice interaction is treated by considering the lattice polarization as discrete.
New scaling variable in the high energy pp collisions at ISR energies and the derived sea level muon spectrum
Authors: Roychowdhury R. K. , Bhattacharyya D. P.
Published: April 2011

The ISR data on p + p → Π− + X reactions can be represented with the help of a scaling variable η = 2 pT2x/ln (s/s0) for 0.075 ≤ x ≤ 0.3 and 0.2 ≤ pT ≤ 1.5 GeV/c. The data at different energies follow the relation[Formula: see text]where s0 = 1 GeV, A = 46.06, a = 85, and b = 510. This scaling variable has been used to derive the sea level muon spectrum and the result agrees with the magnetic spectrograph data.
Comment on plane gasdynamic flows in an orthogonal magnetic field
Authors: Lai C. S.
Published: April 2011

The steady two-dimensional magnetogasdynamic flows are classified for when the fluid pressure is governed by the general gas law p = p(ρ). This is a generalization of Kingston's work in which the pressure–density relation is assumed to be pρ−γ = constant.
Laboratory simulation of the stepped leader in lightning
Authors: Kekez M. M. , Savic P.
Published: April 2011

It is shown that the 'stepped leader' often observed in lightning discharges is a manifestation of the nonlinear characteristic of the glow surrounding the leader tip, together with the parallel resistance–capacity behaviour of the far-field region. The resulting relaxation oscillations lead to intermittent discharges, which are simulated by adding resistance and capacity to the external circuit of a standard discharge gap experiment.In addition, two complementary experiments were carried out to further illustrate that the stepped leader is subject to a continuous sequence of 'run-stop' conditions, whereby the fast transient displacement current pulse is a manifestation of the 'run' state. A uniform view of the stepped leader and leaders propagating in well-preionized gas, in which displacement current is absent, is presented. This interpretation is largely confirmed by the present experiments as well as those of Gänger and Maier.
Theoretical oscillator strengths III. Transitions in Au I, Hg II, Pb IV, and Bi V spectra
Authors: Migdałek J.
Published: April 2011

In the course of this investigation the relativistic oscillator strengths were calculated for some transitions in the principal, sharp, and diffuse series of the Au I, Hg II, Pb IV, and Bi V spectra. The radial integrals were computed employing the wave functions for the active electron obtained by a semiempirical approach which allowed for exchange effects. A comparison between the calculated line and multiplet f values and the other available experimental and theoretical data is presented. The influence of the relativistic effects on the oscillator strengths values for the transitions under consideration is discussed.
A proton FFT study of the aromatic and alkyl motions in the liquid crystal CBOOA: Orientational order fluctuations in the isotropic phase
Authors: Visintainer J. J. , Bock E. , Dong Ronald Y. , Tomchuk E.
Published: April 2011

Proton line shapes and spin–lattice relaxation were studied in the isotropic phase of the liquid crystal n-p-cyanobenzylidene-p-n-octyloxyaniline (CBOOA) using Fast Fourier Transform (FFT) spectroscopy. The proton spin–lattice relaxation time T1 above the nematic–isotropic phase transition was measured, at several Larmor frequencies, for the resolved peaks in the FFT spectra. The critical temperature dependences of (T1)cf, the T1, due to collective order fluctuations, are thus studied for the aromatic and the alkyl proton groups. The critical temperature behavior of CBOOA is compared with the predictions of the model based on short-range nematic orientational order fluctuations.
Factorization of the evolution operator for a spin–orbit coupled system in an external magnetic field for an arbitrary L and
Authors: Bogdanović R. , Whitehead M. A. , Gopinathan M. S.
Published: April 2011

The evolution operator of the spin–orbit coupled system in an external magnetic field is factorized according to the operator equation:[Formula: see text]where HSO is the spin–orbit coupled Hamiltonian and HZ is the Zeeman Hamiltonian. The preceding equation is expressed in matrix form using the theory of the O(4) group representations. For the special case of [Formula: see text], an explicit form of the matrix C(t) is found. The operator corresponding to the matrix C(t) is found in a closed form using the projection operators constructed in the Appendix. Two special cases, corresponding to a weak and a strong external field, are considered, and possible applications of the results obtained are indicated.
Multiplexage en communication optique par interféromètrie à grande différence de marche en lumière blanche
Authors: Cielo P. , Delisle C.
Published: April 2011

In a recent publication (Delisle and Cielo) a method of communication by optical waves, based on the variation of fringe interval in the channelled spectrum from a broad band source, was presented. The purpose of the present paper is to show, both theoretically and experimentally, how to construct a multiplex communication system based on this principle, which allows a simultaneous transmitting and receiving of several messages. Within the framework of studying several variables of the system, particular attention is given to the choice of path-length differences in the emitting interferometers. This choice must be within certain constraints in order to avoid crosstalk or reduce it to a negligible level. A slightly different approach is also described, multiplexing by frequency, which presents certain advantages over the first method, multiplexing by wavelength difference, especially where it concerns the intensity of the transmitted light beam as a function of the number of emission sources.[Journal translation]
On the physical content of kinetic Ising models
Authors: Lumsden Charles J. , Trainor L. E. H.
Published: April 2011

It is shown that Glauber's methods are appropriate to the high temperature limit for a stochastic spin system and can be applied to models with arbitrary spin interactions in this limit.
A note on the scattering from transition potentials
Authors: Das J. N. , Datta Madhabi
Published: April 2011

The scattering problem for the non-central transition potential g/r2 sin2 θ/2 has been solved exactly. The result has been compared with those for Coulomb and inverse square potentials.
Theory of the optically pumped cesium maser
Authors: Vanier Jacques , Strumia Franco
Published: April 2011

The theory of the optically pumped cesium maser is given. The density matrix formalism is used. We give the oscillation conditions as well as the expected short term stability. A numerical example is discussed in which we assume the use of a confocal Fabry–Perot resonator for the microwave cavity.
Radio auroral scattering anisotropy inferred from 42 MHz polarization studies
Authors: Bédard N. , Sofko G. J.
Published: April 2011

Polarization measurements of 42.1 MHz continuous-wave (CW) backscatter made on two occasions during 1973–1974 are reported. When the orientation (ψ), ellipticity (χ), and polarization ratio ratio (m) are plotted vs. intensity, they exhibit a more well-defined behaviour at high intensities than at low intensities, so only the former case is discussed. The most striking feature of the results is that the received orientation is opposite to that expected on the basis of Faraday rotation, which implies that the scattering process must be an important factor in modifying the polarization state. To explain the results, a simple three-stage model of auroral backscatter is presented involving Faraday rotation [Formula: see text] on the way to the scatterer, anisotropic scattering, and equal Faraday rotation [Formula: see text] on the return path from the scatterer. Using the above model, one must invoke an anisotropic scattering process which introduces a phase anisotropy of 180° between the electric field components parallel and perpendicular to the earth's field, and an amplitude anisotropy ratio in the range 2:1 to 4:1 for these components respectively. There is a received polarization ratio of about 0.95, which can be explained readily by introducing into the model some spread, both in the amplitude anisotropy of the scatterers and in the Faraday rotation, the latter spread being due to spatial separation of the scatterers.
Determination of the spin-splitting factor gc for Landau levels from the first three harmonics in the de Haas–van Alphen effect
Authors: Gold A. V. , Schmor P. W.
Published: April 2011

A simple and convenient method is proposed for extracting the spin-splitting factors gc associated with extremal orbits around the Fermi surface from knowledge of the amplitudes Ar of the first three harmonics in the de Haas–van Alphen effect. In the approach suggested here, the quantity of prime interest is the dimensionless ratio α = A22/A1A3, which is independent of both the detailed shape of the Fermi surface and the Dingle temperature. Information about the relative phases of the harmonics allows corrections to be made for the Shoenberg magnetic interaction.In a first application of this three-harmonic method, the dHνA waveform has been studied in disk-shaped samples of Pb using a sensitive magnetoresistive-probe technique, and gc has been determined for the orbits ν and ν′ on the third-zone electron surface. We have also attempted to calculate the splitting factors within the framework of the 4 OPW band-structure model of Anderson, O'Sullivan, and Schirber. However, the simplification of using 4 OPW's throughout the Brillouin zone is found to lead to serious errors and inconsistencies as far as these differential magnetic quantities are concerned.
The Rayleigh–Brillouin spectrum of compressed H2; a test of translational hydrodynamics
Authors: Hubert M. , May A. D.
Published: April 2011

This paper reports on a comparison between the observed Rayleigh–Brillouin spectra of compressed hydrogen and those computed according to the translational hydrodynamic theory of Desai and Kapral. Reasonable agreement is found in the range of densities from 19 to 61 amagat units. It is suggested that small residual discrepancies may be due to the neglect of part of the coupling between the energy and momentum fluctuations arising from relaxation of the rotational states, i.e. due to the neglect of the 1ν1 terms.
Some electrical properties of a-CdS films
Authors: Barlow S. M. , Brodie D. E.
Published: April 2011

Thin films of a-CdS have been prepared by vacuum deposition. DC conductivity against temperature measurements for mature films have been interpreted on the basis of the Davis–Mott model. Room temperature Seebeck data have indicated that a-CdS films are n type.
The density dependence of the Hanle effect in the resonance line of atomic barium
Authors: Kelly F. M. , Mathur M. S.
Published: April 2011

The change in the Hanle effect of the singlet resonance line of neutral barium has been studied over a wide range of density. The low density region has been used to confirm a lifetime of 8.37 ± 0.08 ns for the 6s6p1P1 level. We have determined the cross sections for the relaxation of the multipole moment of order 2 for collisions of the excited level with the ground level and with the metastable 6s5d1D2 level, and comparisons are made with the measured value of [Formula: see text] for the ground level with theoretical predictions.
Etude des diverses contributions à l'absorption de l'acétophénone liquide en infrarouge lointain
Authors: Bossis G.
Published: April 2011

The far infrared absorption of acetophenone and of two of its derivatives (p-fluoro and p-chloro) has been measured in the neat liquids. Intramolecular vibrations have been observed at 226, 207, and 181 cm−1 respectively. At lower frequencies a broad absorption is present. This is shown to be composed of: (i) the angular motion of the permanent dipoles of the molecule moving as a rigid body; (ii) the existence of an internal rotation (twisting); (iii) the contribution of temporary dipole-induced dipoles. This latter process is much more important than in less polar molecules.
Coulomb nuclear interference in π−–12C and π±–16O elastic scatterings around the P33 resonance
Authors: Nakano Kouichi
Published: April 2011

π−–12C and π±–16O elastic scattering cross sections are calculated around the P33 resonance and results are compared with experimental data in the small scattering angle region. Novel features of the present calculations are the inclusion of the Coulomb interaction by a momentum space method which is based on the recently proposed coupled integral equations formalism, and the use of the more elaborate nuclear scattering matrix element which is calculated from the multiple scattering theory.