bluuebunny/crossref_metadata_2025 huggingface dataset:
The 7390 Å band of NO2, a vibronically-induced transition within the ground state manifold
Authors: Hallin K-E. J. , Merer A. J.
Published: April 2011

About 160 rotational lines in the region 7370–7410 Å in the electronic spectrum of NO2 have been assigned from high dispersion grating spectra. The lines form the K = 0,1, and 2 sub-bands of a perturbed parallel band where the upper state A rotational constant is about 17 cm−1. In a diabatic representation the band can be considered as a transition within the ground state manifold, which obtains its intensity by vibrational momentum coupling from a nearby band of the [Formula: see text] electronic transition; its vibrational assignment is 2 13 1 – 000. Comparison with the spectrum of 15NO2 shows that the nearby Ã2B2 level has quite a small amount of vibrational energy, which is not inconsistent with the assignment by Brand, Chan, and Hardwick that the (0, 0) band of the [Formula: see text] transition is at 8350 Å. The implications of the electron spin–rotation parameters and the intensity of the 7390 Å band are discussed.
The influence of intracollisional interference on the dipole spectrum of HD
Authors: Tipping R. H. , Poll J. D. , McKellar A. R. W.
Published: April 2011

The influence of intracollisional interference on the dipole spectrum of pure HD is investigated within the framework of an adiabatic separation of the relative translational motion and non-mixing of rotational levels. The effect leads to a density dependence of the integrated intensities for the sharp spectral lines. It is found that the large discrepancy between the theoretical and experimental pure rotational dipole moment matrix elements for HD reported in the literature can be interpreted as destructive interference between the allowed and the collision-induced dipoles. Similar calculations for the fundamental band are in excellent agreement with the experimental results for the R1(1) line, but agree less well for the R1(0) line. We interpret this, as well as the asymmetrical line shape, as evidence of rotational level mixing due to anisotropic intermolecular forces.
Quantum mechanics in rotating frames. I. The impossibility of rigid flow
Authors: Gulshani P. , Rowe D. J.
Published: April 2011

The Hamiltonian describing a system of particles in a rotating coordinate system is derived and it is shown that the simple classical solution of rigid flow is forbidden in quantum mechanics, even at very low angular velocities. This effect is closely parallel to the Aharonov–Bohm effect, which likewise has its origin in the single-valuedness requirement of the wave function. An analytical approach to perturbation theory is used to include the effects of the Coriolis and centrifugal forces and to derive the current flows for some independent-particle systems, that is, for the Inglis cranking model. It is shown, by explicit construction, that the currents are not rigid even when the moment of inertia assumes the rigid-flow value, as it does for the harmonic oscillator single-particle potential under conditions of self-consistency. Furthermore, it is shown that, for a more general potential, even the moment of inertia is not rigid.
High resolution rotation–vibration Raman spectra of benzene. II. The doubly degenerate bands of C6H6
Authors: Hollinger A. B. , Welsh H. L.
Published: April 2011

The Raman spectrum of benzene vapour was excited in a multiple reflection Raman cell by an Ar+ laser and was photographed with a spectral slit width of ~ 0.15 cm−1. The results for the five doubly degenerate Raman-active fundamentals are given in this communication. More than 150 maxima were resolved in the ν17 band and the spectrum was analyzed with a computer program to give ν17 = 1177.776(10) cm−1, B1 – B0 = 1.00(4) × 10−4, C1 – C0 = −0.50(2) × 10−4 cm−1, and ζ17 = 0.010(1). About 60 maxima were recorded in the ν18 band; molecular constants were determined but with less precision than for ν17. The ν15 band (partially overlapped by ν1) and the (ν16, ν2 + ν18) Fermi diad showed resolved structure but no detailed analyses were possible. The ν11 band showed no resolved structure.
Operation of a long helium jet transport system with solid, monodisperse aerosols
Authors: Venkatasubramanian V. S. , Barber R. C. , Ellis R. J. , Derenchuk V. P. , Sharma K. S. , Duckworth H. E.
Published: April 2011

Solid, monodisperse aerosols of NaCl, KCl, and AgCl have been used in a helium jet capillary system to transport unstable nuclides of Cu, Zn, Ga, and Sb a distance of 110 m. Overall transport efficiencies of ~ 60% have been achieved.
Use of Al analyzing power
Authors: Shahabuddin M. A. M. , Buja-Bijunas L. , Stott W. R. , Waddington J. C.
Published: April 2011

The [Formula: see text] Al cross section and analyzing power angular distributions were measured at Ep = 17.0 MeV. The fits to the cluster DWBA calculations have shown that the analyzing power can play an important role in the determination of the correct optical model parameters.
Improved laser frequencies and Dunham coefficients for isotopically substituted carbon monoxide
Authors: Dale R. M. , Herman M. , Johns J. W. C. , McKellar A. R. W. , Nagler S. , Strathy I. K. M.
Published: April 2011

New measurements of carbon monoxide laser frequencies in the 5.3 to 7.2 μm region have been made using the techniques of infrared grating spectroscopy and heterodyne beat frequency detection. The observations concentrated on the rarer isotopic species 13C16O, 12C18O, and 13C18O, and on the lower frequency region of CO laser oscillation, where less data have previously been available. The new results have been combined with a large amount of previous data in a simultaneous least-squares fit involving all known isotopic species of CO. The resulting parameters are a set of 'reduced' Dunham coefficients and a set of mass-scaling factors which describe how their isotopic variation differs from the simple mass-dependence normally assumed. Laser frequencies calculated from the new Dunham coefficients are improved from those previously available, especially in the relative accuracy of each isotope compared to the others, and they should prove useful in spectroscopic applications of the CO laser. Comprehensive tables of Dunham coefficients for all CO isotopes and of calculated laser frequencies for 12C16O,13C16O, 12C18O, and 13C18O are given in the paper and in an Appendix.
Nernst–Wienecke equilibrium in linear magnetized plasmas
Authors: Ahlborn Boye
Published: April 2011

A cylindrical hydrogen plasma imbedded in a strong axial magnetic field, in which a temperature maximum is maintained by axial heating and radial heat transfer, has a pressure maximum and a density minimum on axis. The pressure in dyn/cm2 and density in cm−3 can be approximated as [Formula: see text]BT3/4 and [Formula: see text]BT−1/4 (B in gauss and T in kelvin).
Study of high spin states in 149Tb observed by the (10B,3n) reaction
Authors: Singhal N. C. , Johns M. W. , Thompson J. V.
Published: April 2011

Energy levels in 149Tb have been studied by the 142Nd (10B,3n) reaction using 54 MeV 10B beams from the McMaster University FN accelerator. Excitation functions, angular distributions, prompt γ–γ coincidence, electron conversion, and linear polarization measurements were obtained. On the basis of these measurements we have identified two rotaition-aligned πh11/2 bands, a negative parity band up to spin 27/2−, and a positive parity band up to spin 27/2+. The energy spacings between levels in these bands strongly resemble those in the ground state and the 3− octupole band of the adjacent 148Gd core nucleus. Other high spin positive parity states up to spin of 41/2 are also observed. These high spin states show some evidence of rotational structure in 14 9Tb.
Use of rescreened pseudopotentials for the superconductivity of aluminum at finite pressures
Authors: Whitmore M. D.
Published: April 2011

Use is made of the pseudopotential determined by Dagens, Rasolt, and Taylor to calculate from first principles all the microscopic phonon and electron–phonon properties necessary for the superconducting transition temperature of aluminum, Tc, for zero pressure and for volume changes up to −10%. After fitting the Coulomb pseudopotential parameter μ* at zero pressure, Tc is calculated both by solving the Eliashberg gap equations on the imaginary axis, and by employing the approximate formulae of McMillan and of Leavens. The resulting pressure dependence of Tc is unsatisfactory. One source of error appears to be an insufficient pressure-induced shift of the phonon frequencies, indicating a limitation on the use of these pseudopotentials that is not widely appreciated. However, this is not believed to be the only difficulty and other possibilities are briefly discussed.
The realization of the internationally adopted "Josephson volt" in Canada
Authors: Wood Gordon H. , Dunn Andrew F.
Published: April 2011

The internationally accepted Josephson volt, which corresponds to 2e/h = 483 594.0 GHz/VBIPM-69, was adopted 1 July 1978 as the primary reference for the Canadian volt (VNRC). Emphasis is given to a description of the experimental apparatus and techniques used to realize the Josephson volt at the National Research Council to an estimated overall uncertainty of ± 0.12 ppm (1σ).
Diffraction by a half plane perpendicular to the distinguished axis of a gyrotropic medium (oblique incidence)
Authors: Przeździecki S. , Hurd R. A.
Published: April 2011

An exact, closed form solution is found for the following half plane diffraction problem. (I) The medium surrounding the half plane is gyrotropic. (II) The scattering half plane is perfectly conducting and oriented perpendicular to the distinguished axis of the medium. (III) The direction of propagation of the incident electromagnetic plane wave is arbitrary (skew) with respect to the edge of the half plane. The result presented is a generalization of a solution for the same problem with incidence normal to the edge of the half plane (two-dimensional case).The fundamental, distinctive feature of the problem is that it constitutes a boundary value problem for a system of two coupled second order partial differential equations. All previously solved electromagnetic diffraction problems reduced to boundary value problems for either one or two uncoupled second order equations. (Exception: the two-dimensional case of the present problem.) The problem is formulated in terms of the (generalized) scalar Hertz potentials and leads to a set of two coupled Wiener–Hopf equations. This set, previously thought insoluble by quadratures, yields to the Wiener–Hopf–Hilbert method.The three-dimensional solution is synthesized from appropriate solutions to two-dimensional problems. Peculiar waves of ghost potentials, which correspond to zero electromagnetic fields play an essential role in this synthesis. The problem is two-moded: that is, superpositions of both ordinary and extraordinary waves are necessary for the spectral representation of the solution. An important simplifying feature of the problem is that the coupling of the modes is purely due to edge diffraction, there being no reflection coupling. The solution is simple in that the Fourier transforms of the potentials are just algebraic functions. Basic properties of the solution are briefly discussed.
Low-lying states of TeF: observation and assignment of the A and B states
Authors: Newlin Donald E. , Stewart Gerald W. , Gole James L.
Published: April 2011

Low-lying electronic states of TeF, whose emission results when hydrogen telluride and fluorine are intimately mixed, are reported. The emission spectrum in the region 5500–8600 Å would appear to result from the A2Πi–X2Πi transition. Based upon this observation, the previously reported system in the region 3900–5200 Å must be reassigned to the transition B2Σ+–X2Πi. Observed spectra are presented and vibrational and electronic constants for the A2Π, B2Σ+, and X2Π electronic states are tentatively assigned.
Photoluminescence in laser-annealed neutron transmuted silicon: isoelectronic traps
Authors: Rostworowski J. A. , Parsons R. R.
Published: April 2011

A Q-switched ruby laser is used to laser-anneal neutron transmuted silicon. The starting material was ultra high purity silicon. Approximately 2 × 1014 P/cm3 were created by the neutron transmutation doping. Photoluminescence measurements at T = 1.7, 4.2, and 20 K revealed long-lived sharp emission lines which were identified with an isoelectronic trap remaining in the laser-annealed material. P-related luminescence was not observed before or after laser annealing.
The detection of phase transitions in NH4Sm(SO4)2∙4H2O single crystals using the electron paramagnetic resonance of Gd3+ impurity ions
Authors: Buckmaster H. A. , Malhotra V. M. , Bist H. D.
Published: April 2011

The 9.4 GHz electron paramagnetic resonance (epr) of Gd3+ impurity ions in NH4Sm(SO4)2∙4H2O single crystals has been studied at 101–297 K. The 294 K epr spectra show that the Gd3+ impurity ion substitutes for the Sm3+ host ion in two magnetically nonequivalent complexes corresponding to the tetramolecular unit cell. These spectra were analyzed using an orthorhombic symmetry spin-Hamiltonian. The observation of resolved Gd3+ impurity ion spectra in the presence of paramagnetic Sm3+ ions has been interpreted in terms of a random modulation of the interaction between the Gd3+ impurity and Sm3+ host ions by rapid spin–lattice relaxation of the Sm3+ ions. The spin–lattice relaxation time of the Sm3+ ions has been estimated at 294 K from the impurity ion epr linewidths and is found to be consistent with an Orbach resonance process. The value for τ1, has also been computed for Nd3+ ions in NH4Nd(SO4)2∙4H2O from the epr linewidth data in the literature. It has been shown for the first time that NH4Sm(SO4)2∙4H2O single crystals have the phase transition sequence[Formula: see text]
Mode-locking by an intracavity plasma. Part II. Experimental results
Authors: Piché M. , Bélanger P. A.
Published: April 2011

The results of an experimental investigation of TEA-CO2 laser mode-locking by an intracavity plasma are described in this paper. The observations evidence the critical role played by the plasma switching process; complete mode-locking was consecutive to a fast cutoff of the gain-switched laser pulse. The laser beam was focussed by the plasma at the instant of gas breakdown. The short pulse trains were depolarized, even though the gain-switched pulse producing the plasma was plane polarized. The plasma was shown to both reflect and transmit laser light by moving its relative position in the laser cavity. The results are discussed in terms of a model involving the combination of an amplitude shutter and a frequency shifter. We establish the relationship between our experiment and similar ones reported in the literature.
Tunneling into a superconducting proximity sandwich
Authors: Smith H. J. T. , O'Byrne T.
Published: April 2011

Measurements and calculations have been made of the Cooper pair current tunneling into the superconducting side of a proximity effect sandwich.
Experimental study of passive laser pulse compression in a fluorescent dye medium
Authors: Faubert D. , Chin S. L.
Published: April 2011

We present an experimental study of the passive propagation of a long laser pulse in a fluorescent dye medium showing the importance of stimulated emission. Enhanced transmission as well as compression of the laser pulse were observed.
Internal Schottky barriers in semiconductors
Authors: Weichman F. L.
Published: April 2011

We discuss the effect on the electrical conductivity of a semiconductor if small metal inclusions are formed within the bulk of the semiconductor where the metal to semiconductor contact is a rectifying one. We find that the depletion layers formed inside the material can dominate the conduction process and give rise to conditions similar to that of a highly compensated semiconductor with highly variable activation energy. Some of the predictions of the model are compared to observed facts in cuprous oxide and are shown to be consistent with observation. The expected behaviour of a semiconductor with internal injecting contacts is also briefly discussed.
The instantaneous relationship between polar cap and oval auroras at times of northward interplanetary magnetic field
Authors: Murphree J. S. , Anger C. D. , Cogger L. L.
Published: April 2011

Optical images of the polar cap region at both 5577 and 3914 Å obtained from 1400 km above the earth have been used to study the relationship between polar cap and oval aurora during periods when the interplanetary magnetic field is strongly northward, i.e., B2 > 3.5 nT. When this rather rare condition occurs, the distinction between the two types of aurora is no longer as clear as depicted on the basis of statistical definitions of the auroral oval. Diffuse, weak emission can fill in the region between the auroral oval and discrete auroral features in the polar cap. The polar cap discrete features can appear very similar to auroral oval arcs in intensity, intensity ratio, and structure. Even more striking are the situations where discrete polar cap features merge with oval auroras. From this study it is concluded that under conditions of large positive B2 the region of closed magnetic field lines can expand poleward to occupy much of the high latitude region.
Normal metal point contacts
Authors: Kempen H. van
Published: April 2011

Under conditions of extremely high current densities, deviations from the linear current (I) – voltage (V) relation (Ohm's law) occur in normal metals. One can obtain sufficiently high current densities (of the order of 1010 A/cm2) by applying a voltage to a point contact. The nonlinear Boltzmann equation relates the nonlinearities to the energy dependence of the electron scattering probabilities. It is shown, for example, that d2V/dI2 is proportional to α2(ω)F(ω), where F(ω) is the phonon density of states and α(ω) is the electron–phonon scattering matrix element. In addition other interactions arc studied by this method such as electron–magnon interaction and the interaction of electrons with paramagnetic impurities, the well-known Kondo effect. A double point contact geometry is described which allows electron–surface scattering to be studied.
Review of the Fröhlich sliding mode in NbSe3
Authors: Ong N. P.
Published: April 2011

The anomalous transport properties of the charge-density-wave system niobium triselenide are surveyed. Early experiments on the frequency dependence and non-ohmicity of the electrical conductivity are described together with interpretations using the sliding mode mechanism. The effect of impurities, the non-ohmic Hall effect, conduction noise, and ac conduction are described. Theoretical models which have been proposed arc discussed, together with difficulties from the experimental viewpoint. Lastly, mention is made of recent experiments on NbSe3 as well as other similar systems.
The interaction of conduction electrons with dislocations and grain boundaries in metals
Authors: Brown R. A.
Published: April 2011

Progress in understanding the contributions of dislocations and grain boundaries to the residual electrical resistivity in metals is reviewed. Following a summary of experimental data on dislocation and grain-boundary resistivity, it is shown that the resistivity due to the latter can be simply understood in terms of the independent scattering of electrons by individual dislocations of the ordered arrays which form the boundaries. The significance of this observation in establishing the relative dominance of dislocation core scattering over strain-field scattering, so far as charge transport is concerned, is discussed. A brief review of the multitude of dislocation–electron scattering calculations which have appeared in the literature is presented. This shows that theories which neglect the core contribution have invariably failed to account for the order of magnitude of the observed resistivity, again suggesting that core scattering dominates the issue. A simple formula derived from a resonance model of the core-electron interaction is shown to yield dislocation (and hence grain-boundary resistivity) contributions in good agreement with experiment.
Sharp-line, donor–acceptor pair recombination luminescence in Si(In,Li), Si(Ga,Li), Si(Al,Li), and Si(B,Li)
Authors: Ziemelis U. O. , Thewalt M. L. W. , Parsons R. R.
Published: April 2011

The observation of sharp-line, donor–acceptor pair recombination luminescence in Si following the diffusion of the donor Li into samples previously doped with the acceptors B, Al, Ga, or In is reported. Shell assignments have been made for most of the numerous new photoluminescence lines. These assignments indicate that the principal donor introduced into the samples was the Li–O complex, and that the principal acceptor in the In-doped samples was the In–X centre. Results for the Al- and Ga-doped samples are consistent with ordinary Al and Ga acceptors, while those for B are inconclusive due to the extreme weakness of the sharp-line structure. This study not only confirms that donor–acceptor pair recombination in Si can give rise to sharp luminescence line series, but shows that this process is quite widespread, given the proper concentrations of donors and acceptors.
Resonance fluorescence intensities and vibrational assignments in the A2B2 state of NO2
Authors: Brand J. C. D. , Cross K. J. , Hoy A. R.
Published: April 2011

The intensity of NO2 resonance fluorescence excited at several wavelengths in the range 5930–6480 Å has been measured as a function of final state vibrational quantum numbers. Calculations based on these Franck–Condon profiles establish the relative vibrational assignments of five bands in the [Formula: see text] system. In one case, the similarities between a Ka = 1 and a Ka = 6 profile lead to a value of the Ã 2B2A rotational constant of ~3.0 cm−1. The influence of Franck–Condon profiles on the radiative lifetime of pure Ã 2B2 states is investigated.
Temperature dependence of the pair correlation function in an inhomogeneous liquid: application to C24Cs
Authors: Plischke Michael , Leckie W. D.
Published: April 2011

We study the properties of a model appropriate to stage 2 graphite intercalation compounds such as C24Cs and C24K. The Hamiltonian consists of an effective pair potential for the intercalate and a periodic background potential due to the graphite lattice. We obtain the pair correlation function over the range of temperatures 0–300 K. We find orientational effects and compare our results with data on C24Cs.
Optical absorption in polar crystals with several LO phonon branches
Authors: Lépine Y. , Kartheuser E.
Published: April 2011

The optical absorption by free and bound polarons in polar crystals with several LO phonon branches is described in the adiabatic approximation. In both cases, we calculate both zero and one phonon absorption. For free polarons, we find a behaviour similar to that obtained for the one LO phonon branch case. Additional structure can, however, appear in the Franck–Condon relaxation part of the spectrum. For bound polarons, we find that the oscillator strength of the one phonon replica associated to the ith phonon branch is proportional to its coupling constant and inversely proportional to the square root of the phonon frequency. A discussion of these results is made in relation to recent infrared spectra obtained in perovskites.
A Mössbauer study of a single crystal of the β phase of iron–germanium
Authors: Daniels J. M. , Lam H. Y. , Li P. L.
Published: April 2011

57Fe Mössbauer spectra were obtained by scattering in a narrow angle geometry from a face, containing the basal plane, of a single crystal of the hexagonal β phase Fe1.67 Ge. Spectra were also obtained from a source of 57Co diffused into an a–c face of a single crystal of this alloy. In all cases, the spectra were satisfactorily resolved into three six-line patterns, and measurements of the relative intensities of the lines indicate that the antiferromagnetic state has a canted structure with all the spins lying in the basal plane.
Laser magnetic resonance spectrum of 13CH2 around 11 µm: determination of 13C hyperfine interactions and ν2 isotope shift for methylene
Authors: McKellar A. R. W. , Sears Trevor J.
Published: April 2011

Ten rotation–vibration transitions of the ν2 (bending) fundamental band of 13CH2 have been observed using the technique of CO2 laser magnetic resonance in the 880 to 945 cm−1 region. 13C substituted methylene was produced in a flow system by reacting 13CH4 or 13CH2CO with F atoms from a microwave discharge in CF4. Analysis of the spectra yields a number of molecular parameters for 13CH2. Specifically, the 13C isotope shift of ν2 is −3.93 cm−1 and the 13C Fermi contact hyperfine parameter is 238 ± 6 MHz for the ground vibrational state. The hyperfine parameters determined here for gas phase 13CH2 are in fairly good agreement with those determined for matrix isolated 13CD2 in earlier ESR experiments.
A test apparatus for secondary ion mass spectrometry
Authors: Klaus N. , Brown J. D.
Published: April 2011

A low cost test device for secondary ion mass spectrometry (SIMS) components is described. It consists of a turbomolecular pumped vessel containing an insulated sample stage on an x−y manipulator, extraction optics, quadrupole mass filter, and channel electron multiplier. The construction and characteristics of a cylindrical and a spherical saddlefield ion source are described. The output of the cylindrical source is 10−4 A cm−2 whereas that of the spherical source is in the order of 10−3 A cm−2 at voltages up to 9 kV and at a beam divergence of 4°.
Champs électromagnétiques dans une cavité sphéroïdale conductrice : nouvelles équations intégrales permettant une solution numérique simplifiée
Authors: Imbeau Jacques A. , Darling Byron T. , Amiot Pierre
Published: April 2011

New integral equations (Darling and Imbeau; Imbeau and Darling) from a generalized Huygens principle allow the calculation of electromagnetic fields and resonance frequencies in a conducting spheroidal cavity excited by an elementary Hertz dipole in the cavity. These equations separate into surface integral equations for the fields observed inside the cavity and null surface integral equations. The latter have a regular kernel and this permits the calculation of all the fields on the surface. The ensuing simplification allows an easy calculation of the resonance frequencies with the precision of all 16 significant digits available on an IBM-370 working in double precision.
The scattering of positive kaons by nuclei
Authors: Krell M. , Thomas A. W.
Published: April 2011

We examine the sensitivity of low energy positive kaon (K+)–nucleus scattering to the neutron distribution. By using the technique of isotope comparison which has worked well for low energy pions, we find that there seem to be "windows" where one could already learn something quantitative about the neutron distribution despite the poorly known K+–nucleon phase shifts.
Rapidity distribution of shower particles in proton–nucleus interactions in emulsions at 70 GeV
Authors: Ghosh G. C. , Bandyopadhyay B. K.
Published: April 2011

Nuclear emulsion plates exposed to 70 GeV protons have been scanned for inelastic interactions. The rapidity distribution of the shower particles observed in 132 events are presented. The dependence of rapidity on the target nucleus mass number has been studied and compared with the results for other energies obtained by earlier workers. The individual rapidity of the shower particles observed in some high multiplicity events are also shown. The qualitative features of the observed rapidity distributions are found to agree with the Glauber–Gribov multiperipheral model.
Eikonal phase shift analyses of carbon–carbon scattering
Authors: Townsend L. W. , Bidasaria H. B. , Wilson J. W.
Published: April 2011

A high-energy double-folding optical potential approximation to the exact nucleus–nucleus multiple-scattering series is used to determine eikonal phase shifts for carbon –carbon scattering at 204.2, 242.7, and 288.6 MeV. The double-folding potentials are obtained by folding the energy-dependent free nucleon–nucleon interaction with densities for the projectile and target obtained by unfolding the finite nucleon charge density from harmonic-well carbon charge distributions. The charge parameters for the latter are taken from the results of electron scattering experiments. Predictions for total, reaction, and elastic differential cross sections, using standard partial wave analysis for the scattering of identical particles, are made and compared with recent experimental results. Excellent agreement is obtained although there are no arbitrarily adjusted parameters in the theory.
The magnetic resonance lineshape for atomic hydrogen confined by liquid helium walls
Authors: Morrow M. , Hardy W. N.
Published: April 2011

Zero field hyperfine resonance of atomic hydrogen gas confined in liquid helium coated containers is shown to be a versatile technique for studying the interaction of atomic hydrogen with the surfaces of liquid 3He and 4He. Using a simple but realistic model for the effects of collisions with the helium walls, a general result is obtained for the time dependence of the amplitude and phase of the magnetization following a radio frequency magnetic field pulse. It is then shown how binding energies, sticking coefficients, and the distribution of times between sticking events can be obtained. As an example, we present the analysis of experimental data from which the previously reported sticking probability for H on 3He was obtained, and corrected data from which a value of 0.046 is obtained for the sticking probability of H on 4He.
Upper-hybrid solitons
Authors: Shivamoggi Bhimsen K.
Published: April 2011

Modulational instability and formation of envelope solitons of the upper-hybrid waves are considered. A more consistent calculation is given here which also includes the effect of ion inertia. A strong magnetic field can eliminate the existence of subsonic upper-hybrid solitons but can make possible the existence of supersonic upper-hybrid solitons. In order to describe the upper-hybrid solitons travelling at the speed of sound, the ion nonlinearity is included in the calculation with the assumption of charge neutrality in the low frequency plasma response. An exact soliton solution moving at the speed of sound is then exhibited. Finally, a fully nonlinear theory of the formation of envelope solitons of upper-hybrid waves is given. The assumption of charge neutrality in the low frequency plasma response is abandoned. The solution shows a smooth transition from a single-hump soliton as the Mach number increases to unity. Furthermore, the dip at the centre for the double-hump soliton is found to become smaller as the magnetic field becomes stronger.
Syntonisation fine des lasers par un interféromètre intracavité renfermant un gaz absorbant
Authors: Izatt Jerald R. , Mathieu Pierre
Published: April 2011

Laser emissions can be tuned to an absorption line of a gas if the usual output coupler is replaced by a Michelson interferometer with a cell containing the absorbing gas introduced in one of its arms. For a TEA-CO2 laser, this method allows one to tune the emission spectrum over a frequency range equal to the width of the gain curve (3.5 GHz) while maintaining the spectral width around 70 MHz. The analysis of such a system is carried out by taking into account anomalous dispersion and saturation of the absorbing gas. This enables one to determine the optimal values of the experimental parameters and to evaluate the tuning range and the energy efficiency of the laser. Many other practical considerations are also discussed in the text. [Translated by the journal]
Viscoelastic properties of liquid pentachlorobiphenyl under pressure using depolarized light scattering
Authors: Bezot P. , Hesse-Bezot C. , Pruzan Ph.
Published: April 2011

A study of the depolarized light scattering spectra of high pressure supercooled pentachlorobiphenyl is presented. From the analysis of the propagative shear doublet, the infinite shear modulus Gx is measured over a large pressure range, at various temperatures, up to a pressure where the liquid is in a glassy state. Gx(P) is found to vary linearly at each temperature. From values of Gx (P = 0.1 MPa) together with those obtained in a previous paper at P = 0.1 MPa as a function of T, it is concluded that Gx(T) is linear over 70 °C, contrary to what is generally obtained in most of the supercooled molecular liquids.
The S(0) line in solid H2
Authors: Buontempo U. , Cunsolo S. , Dore P. , Nencini L.
Published: April 2011

The far infrared absorption spectrum of solid H2 has been measured in the frequency region of the S(0) line. We have performed measurements at different ortho H2 concentrations in order to investigate the influence of ortho H2 molecules. By increasing the ortho H2 concentration Co from Co = 10% up to 75%, we found that the excitonic absorption is the dominant feature of the S(0) line at low Co values, but it still exists when Co is relevant.
Absorption spectrum of atomic iodine (I I) in the 1040 – 1600 Å region
Authors: Sarma V. N. , Joshi Y. N.
Published: April 2011

The absorption spectrum of atomic iodine (I I) has been photographed in the region 1040 – 1600 Å on a 3-metre normal incidence spectrograph. The atomic vapors of iodine were produced by the flash pyrolysis technique using CdI2 and PbI2 powder salts. The Garton flash lamp was used as the background continuum. Out of the sixteen series reported, starting from the 5s2 5p52P03/2 level, six limited on 5p43P2, six on 5p43P1, three on 5p43P0, and one on 5p41D2 of I II. The earlier analyses have been confirmed and extended. Sixty-two additional lines have been classified in the I I spectrum
Perturbations dans l'état de Se2
Authors: Jenouvrier A.
Published: April 2011

A new analysis of the absorption spectrum of the [Formula: see text] transition of Se2 has been performed. All the perturbations observed in the [Formula: see text], ν = 0 to 6 levels are consistent with two distinct A3Π(1u) and A′1Π(1u) perturbing states which are not responsible for the predissociation near 27 700 cm−1 in the ν = 6 level. A partial deperturbation yields equilibrium constants and electronic interaction elements. The assignment of different electronic states in the energy region under consideration is discussed.
Parity, time, charge and Hermitian conjugations of Racah tensor operators
Authors: Chatterjee R. , Tuszyński J. A. , Buckmaster H. A.
Published: April 2011

The relationship between the parity P, time θ, charge C, and Hermitian h conjugation operators and the irreducible Racah tensor operators is reexamined. Polar tensor operators (describing electric properties) are distinguished from axial tensor operators (describing magnetic properties and angular momenta) on the basis of their individual parity and time conjugation properties. However, the effect of the Pθ product conjugation is identical for both classes and for even rank is equivalent to the Racah definition for the Hermitian conjugation of a tensor operator. It is shown that this property separates the Racah tensor operators from other vector quantities like linear momentum which cannot be represented by such operators. The selection rules due to parity and time conjugation and Hermitian conjugation that arise in the calculation of the matrix elements of the tensor operators and their products are then obtained self-consistently using the Wigner–Eckart theorem.
Cross sections and thermonuclear reaction rates for the 28Si(α, p)31P and 54Fe(α, p)57Co reactions
Authors: Buckby M. A. , King J. D.
Published: April 2011

Absolute cross sections for the 28Si(α, p)31P and 54Fe(α, p)57Co reactions have been measured for laboratory bombarding energies over the range 5.52 ≤ Eα ≤ 12.00 MeV, using targets of approximately 4-keV thickness. Ground state reaction rates were then deduced from these cross sections and stellar rates were deduced by multiplying by the ratio of stellar-to-ground state rates obtained from statistical model calculations. Stellar rates for the reverse reactions have been determined and are fitted by a parametric equation for ease of interpolation. The experimental cross sections and rates have been compared with statistical model calculations and are in reasonable agreement for the 54Fe(α, p)57Co reaction but deviate by as much as a factor of three for the 28Si(α, p)31P reaction.
Seventh spectrum of tin: Sn VII
Authors: VanKleef Th. A. M. , Joshi Y. N.
Published: April 2011

The seventh spectrum of tin was photographed in the 200–550-Å region on a 6.65-m grazing incidence spectrograph at the Zeeman Laboratory in Amsterdam. The source used was a triggered spark. The new observations have led us to analyze the 4d8–4d75p transitions in the Sn VII spectrum. All nine levels of the 4d8 configuration and 97 of 110 levels of the 4d75p configuration have been established. The least-squares-fit energy parameter calculations support the analysis. Two hundred and twenty-one lines have been classified in this spectrum.
Spin-lattice relaxation in solid and liquid CH4–Kr mixtures
Authors: Calvani P. , Luca F. De , Maraviglia B.
Published: April 2011

T1 has been measured at 4 MHz and 78 K < T < 120 K in mixtures having a Kr molar fraction c up to 0.8. The transition temperature Ts, corresponding to the solidus curve, has been determined for several values of c by observing the large discontinuity in T1 as in pure CH4. In the solid phase, the intermolecular dipolar contribution to the relaxation rate is found to be dominant at T > 80 K, and our data are in agreement with a simple model based on the Torrey–Sholl theory. Above the melting point, T1 becomes independent of c, thus suggesting that relaxation may be driven by intramolecular interactions in the liquid phase.
Diffusion of H atoms on the surface of liquid 4He
Authors: Zimmerman D. S. , Berlinsky A. J.
Published: April 2011

The diffusion constant D for H atoms bound to the surface of liquid 4He is calculated from the Boltzmann equation in the relaxation time approximation. The dominant process for momentum relaxation is found to be the emission and absorption of ripplons. Long wavelength ripplons are shown to couple very weakly to bound H atoms, implying a strong temperature dependence of the relaxation time at low T, [Formula: see text] for T < 10−3 K. For the experimental temperature range, 0.1 < T < 0.3 K, [Formula: see text] is rather long, by which we mean that the mean free path [Formula: see text] is several thermal De Broglie wavelengths, Λ, i.e.,l > 30 Λ for T < 0.3 K. We conclude that surface spin relaxation calculations based on binary collisions of freely propagating H atoms are appropriate for H on liquid 4He and that the hydrodynamic contribution to1/T1, due to interactions with ripplons, is negligible.
Photodisintegration of the deuteron
Authors: Hwang W-Y. P.
Published: April 2011

This paper examines those basic theoretical aspects that, in the author's opinion, are relevant for future experimental studies of deuteron photodisintegration, or its time-reversed reaction, at low, intermediate, and high energies. At low photon energies, i.e., [Formula: see text], theoretical aspects stressed by the various authors are contrasted and discussed. At intermediate energies, i.e., [Formula: see text], the major emphasis has to do with the importance of studying the role played by isobars [Δ(1232)], especially in sorting out effects related to substantial energy transfer to the baryonic system. At high energies, i.e., [Formula: see text], the prospect of unraveling manifestations of the quark substructure of hadrons is briefly discussed. For the entire energy region surveyed in this paper, [Formula: see text], it appears essential to measure spin observables so as to disentangle manifestations of the various important aspects relevant for the reaction.
Hydrodynamic interactions: a many-body problem in the theory of suspensions
Authors: Mazur P.
Published: April 2011

A review is given of a recently developed scheme to evaluate the mobility tensors of an arbitrary number of spheres. Some applications and implications are discussed.
A model for charge-density waves in TaTe4 and related materials
Authors: Walker M. B.
Published: April 2011

The proposed model assumes that charge-density waves are formed on equivalent, weakly interacting, one-dimensional columns. Various three-dimensional structures differing in the relative phasing of the charge-density waves on different columns are found, and the charge-density wave structures of TaTe4 and NbTe4 are interpreted in terms of these results.
Atomic momentum distributions in condensed matter
Authors: Sears V. F.
Published: April 2011

The theory of the momentum distribution function for atoms in condensed matter is reviewed and compared with results of deep-inelastic neutron-scattering experiments. We discuss, in particular, the case of classical and almost-classical liquids, harmonic and anharmonic crystals, and solid and liquid 4He. Except for liquid 4He in the superfluid phase, the momentum distribution is always Gaussian to a good approximation. In some cases this Gaussian behavior is of dynamical origin while, in others, it is a consequence of the central-limit theorem. The observed momentum distribution in superfluid 4He provides direct experimental evidence for the macroscopic occupation of the zero-momentum state and the value of the condensate fraction can be obtained.
On the formation of cavitylike small-polaronic states in solid deuterium
Authors: Bose S. K. , Poll J. D.
Published: April 2011

Certain infrared absorption features in tritiated as well as proton-irradiated samples of solid deuterium have been attributed to the formation of bubblelike electronic states localized in the lattice. These bubblelike states are shown to be energetically stable in the Wigner–Seitz model of the crystal and the gap between the ground-state energies in the bubble and the quasi-free states of the electron is calculated. An initial trapping of the electron by a vacancy is assumed in calculating the localized state energy. Calculations based on a continuum model of the solid yield the radius of such bubbles to close agreement with that obtained from the observed Stark shift of the vibrational levels of the neighbouring molecules due to the localized electrons. The model is used to interpret the radiation-induced absorption in proton-irradiated solid deuterium in the spectral region 4000–7500 cm−1.
Intercollisional interference at low temperatures
Authors: Lewis John Courtenay
Published: April 2011

The intercollisional interference dip in the Q-branch of the fundamental band of collision-induced spectra of H2–He mixtures partially fills in at low temperatures. In contradiction to claims that this ia a quantum effect, we show 1. that if the induced dipole moment is exactly proportional to the intermolecular force then the interference dip goes to zero at all temperatures; 2. that the filling-in of the dip is essentially a classical phenomenon and is due mainly to the discontinuity in the distance of closest approach during binary collisions as a function of impact parameter.
Surface electrodynamics: radiation fields, surface polaritons, and radiation remnants
Authors: Sipe J. E. , Driel H. M. van , Young Jeff F.
Published: April 2011

We review and discuss the radiation remnant electromagnetic field structures, comparing them in real and Fourier space with radiation fields and surface polaritons. The roles of radiation remnants and surface polaritons in surface processes involving feedback with the electromagnetic field are discussed in a general way, using laser-induced periodic surface structure as an example.
Chlorine nuclear quadrupole resonance lineshape in the cubic antifluorite K2OsCl6
Authors: Ramia Maximo E. , Armstrong Robin L.
Published: April 2011

Chlorine nuclear quadrupole resonance lineshapes are reported for the cubic antifluorite K2OsCl6 in the temperature range 70–300 K. For temperatures above 172 K the spectrum consists of a single symmetric line; for temperatures below 172 K an asymmetric line is observed which can be represented as a sum of two symmetric lines. The symmetric lines are temperature dependent mixtures of Lorentzian and Gaussian profiles. The explanation is that the nuclear quadrupole resonance lines observed in K2OSCl6 are inhomogeneously broadened by temperature dependent local strains caused by point defects and dislocations.
A nuclear orientation study of a single crystal of the β phase of iron–germanium
Authors: Sabbas A. M. , Chen M. E. , Kravitz P. S. , Gavilano J. , Groves J. L. , Wu C. S. , Daniels J. M.
Published: April 2011

The low-temperature nuclear-orientation technique was applied to two single crystals of Fe1.67Ge, one doped with traces of 54Mn and the other with traces of 60Co, and the magnitudes of the effective hyperfine fields were deduced at these two nuclear sites. An estimate of the spin-lattice relaxation time constant was also found for the MnFe1.67Ge and CoFe1.67Ge systems.
Gravity waves from five simultaneous emissions: OH (6–2), NaD, O2(1Σ), OI–557.7 nm, and the visible continuum
Authors: Molina A. , Lopez-Puertas M. , Lopez-Moreno J. J. , Rodrigo R.
Published: April 2011

Simultaneous data from five atmospheric emissions (OH (6–2), NaD, O2(1Σ), OI–557.7 nm, and the visible continuum) have been used to obtain values of the parameters related to gravity waves. Expressions devoted to obtaining values for the proportionality factors between intensity oscillations of each emission and the induced atmospheric density variations are proposed. The linear theory has been used to obtain results about induced velocities, temperature variations, and the kinetic energy density. The different heights of emission layers allow us to analyze the vertical propagation of the gravity waves. The estimated induced velocities are compared with those derived by using the amplitude increase factor from the linear theory. This comparison shows the behaviour of the amplitude following the linear theory for altitudes below 88–90 km and a deviation from the exponential growth for altitudes above 90 km owing to dissipative effects.
On the vibration–rotational energy levels of the hydrogen molecular ion HD+
Authors: Wolniewicz L. , Poll J. D.
Published: April 2011

A new method for calculating vibration–rotational energies of diatomic molecules is discussed and applied to the case of HD+. This method is designed to obtain accurate results for all vibrational states including those close to the dissociation limit. Nonadiabatic, relativistic, and radiative effects are taken into account for all the bound vibrational states with rotational quantum numbers J ≤ 5; the estimated accuracy is of the order of 0.001 cm−1.
Collisionally induced depolarization of 2P1/2 alkali atoms fluorescence: validity criteria of weak-pumping and broad-line approximations
Authors: Rudecki P. , Chwirot S. , Łęgowski S.
Published: April 2011

The dependence of the circular polarization of the fluorescence of alkali atoms on the intensity and spectral composition of the σ+-polarized exciting D1 line has been investigated by considering the stationary solutions of rate equations for populations of the Zeeman sublevels. The calculations were performed for pumping-light intensities corresponding to those of classical light sources, e.g., radio frequency or microwave discharge lamps, and commonly accepted values of cross sections for collisional relaxation of ground-state and excited atoms. The systematic errors of cross sections for collisional disorientation of 2P1/2 alkali atoms due to the neglect of intensity and spectral composition of the exciting light are estimated.