bluuebunny/crossref_metadata_2025 huggingface dataset:
Identification of HGeCl by chemiluminescence from the reaction of GeH4 with Cl2
Authors: Patel Rajendra I. , Stewart Gerald W.
Published: April 2011

Chemiluminescence from the reaction of germane with chlorine has been observed in the region 4450–5200 Å. This emission has been identified as the [Formula: see text] transition in HGeCl. From the observed transitions, approximate equations for the vibrational levels of the lower and upper electronic states were obtained. Thermodynamic considerations indicate that HGeCl is probably produced by the reaction GeH2 + Cl2 → HGeCl* + HCl which is exothermic by approximately 70 kcal/mol. A continuum centered at approximately 4300 Å and extending into the HGeCl spectrum was identified as resulting from GeCl2*.
Pion charge exchange at rest
Authors: Hasinoff M. D. , Salomon M. , Reitan A.
Published: April 2011

We present a theoretical description of charge-exchange absorption of stopped negative pions by complex nuclei, and estimate some branching ratios for this reaction.
The high temperature – low field expansion of the Ising model from the low temperature – high field expansion
Authors: Katsura Shigetoshi , Yazaki Nobuyoshi , Takaishi Mitsugu
Published: April 2011

The high temperature – low field expansions of the Ising model are derived from the low temperature – high field expansions and the coefficients for several lattices are presented.
Vector analyzing powers for the reaction to a transitional nucleus 147Nd
Authors: Straume O. , Løvhøiden G. , Burke D. G. , Waddington J. C.
Published: April 2011

The [Formula: see text] reaction has been studied using 17 MeV deuterons with a vector polarization of ~0.75 from the McMaster University tandem Van de Graaff accelerator. Measurements were made at 18 angles from 6° to 57.5° using a magnetic spectrograph equipped with a position-sensitive proportional counter in the focal plane. It was found that the [Formula: see text] reaction is a very powerful technique for spin determinations in this mass region as the vector analyzing powers have quite large magnitudes. A DWBA calculation with optical model parameters previously optimized to fit cross-section angular distributions was also successful in predicting the analyzing powers for states of known spin and parity. The measured analyzing powers made it possible to give unambiguous spin assignments for over 15 states for which spin information was previously conflicting, incomplete, or lacking.
Etude des molécules diatomiques. Partie I : Hamiltoniens
Authors: Féménias Jean-Louis
Published: April 2011

Theory of perturbations is used in order to derive homogeneously the diatomic Hamiltonian starting from electronic structure up to the higher orders now necessitated in spectrum analysis, taking into account all the interactions without nuclear spins. A diagrammatic method is presented, enlightening the high orders complex calculations and the physical significance of the parameters. All the calculations are made for electronic states in Hund's coupling cases a, b, intermediate a–b and c tendency, and are suitable for modern numerical approaches. Effects up to fourth order (Λ-doubling in Δ states) are investigated. Application is made for a 4Λ (Λ ≥ 1) states.
Etude des molécules diatomiques. Partie II : Intensités
Authors: Féménias Jean-Louis
Published: April 2011

Theory of perturbations, giving the diatomic effective Hamiltonian, is used for calculating actual molecular wave functions and intensity factors involved in transitions between states arising from Hund's coupling cases a, b, intermediate a–b, and c tendency. The Herman and Wallis corrections are derived, without any knowledge of the analytical expressions of the wave functions, and generalized to transitions between electronic states with whatever symmetry and multiplicity. A general method for studying perturbed intensities is presented, taking in good part the spectroscopic modern numerical approaches. The method is used in the study of the ScO optical emission spectrum.
A shell model of bound multiexciton complexes in silicon
Authors: Kirczenow G.
Published: April 2011

It is shown that many features of the recombination luminescence attributed to bound multiexciton complexes (BMEC) in Si can be understood in terms of a shell model. Zeeman and stress-split spectra of phosphorus BMEC's are explained by the model and luminescence lines which were originally predicted by the model have been observed. A qualitative interpretation of the energies of the BMEC recombination photons is given. The intensities of acceptor bound exciton and BMEC luminescence lines are explained for the first time. A formal treatment of no-phonon recombination in indirect gap semiconductors is given and related to the observed spectra.
Sections efficaces différentielles relatives de diffusion des électrons lents (15 à 100 eV) par le krypton
Authors: Delâge A. , Carette J.-D.
Published: April 2011

A high energy and angle resolution electron spectrometer has been used to study the electroexcitation of krypton. The energy of the incident electrons considered, 15–100 eV, is in a range about which there is little or nothing known at the present time. The relative differential cross sections of excitation by electron impact are calculated from the energy loss spectra of scattered electrons for angles ranging from 0 to 90°. Some conclusions are drawn from the values of these cross sections as a function of the energy of incident electrons and of the scattering angle.
Rotational analysis of bands of the 3400 Å system of disulphur monoxide (S2O)
Authors: Hallin K-E. J. , Merer A. J. , Milton D. J.
Published: April 2011

S2O has been prepared in a flow system, and various bands at the long wavelength end of the 3400 Å electronic transition photographed in absorption at high dispersion. Rotational analysis of the bands at 3235 and 3278 Å has shown that the bands are type A–B hybrids, with the type A component accounting for nearly all the observed structure. The electronic transition is therefore 1A′–1A′ (ππ*). The rotational constants imply the upper state structure r(S—S) = 2.14 Å, [Formula: see text], with r(S—O) = 1.50 Å (assumed).The vibrational intensity pattern is found to be in agreement with this structure if the electronic origin is placed at 29 696 cm−1 (3367 Å).
Collision studies with a single molecular beam
Authors: Baylis W. E.
Published: April 2011

Collision rates of some excited-state processes can be studied at low effective temperatures with a single atomic or molecular beam. Effects dependent on the orientation of the collision axis can also be observed in resonant collisions. Useful relative-velocity distributions are given.
Non-local exchange-correlation effects on the spin susceptibility and thermal density of states of Cu
Authors: Liu K. L. , MacDonald A. H. , Vosko S. H.
Published: April 2011

A variational-principle–spin-density-functional approach has been used to investigate the importance of non-local exchange-correlation effects on the spin magnetic susceptibility χp, of Cu. These effects are contained in two functionals, one of which gives the exchange-correlation part of the effective single-particle potential while the other gives an effective spin–spin interaction. For the former functional we have compared two empirically based choices with the commonly used local approximation. The differences between these single-particle potentials are shown to be of the same magnitude as the lowest order density gradient corrections to the local approximation and produce appreciable (~ 5%) effects on the single-particle density of states at the Fermi surface and on the density functional analog of the Stoner parameter I through changes in the single particle spin magnetization. To assess the importance of these non-local corrections, we have calculated the exchange-correlation contributions to the electronic thermal density of states by the density functional theory and find that they are necessary to bring theory and experiment into agreement. The non-local effects of the spin–spin interaction functional on I are investigated by using several non-local approximations based on calculations of the wave vector dependent spin susceptibility for the uniform electron gas system. On the basis of these investigations we conclude that non-local exchange-correlation effects on χp will be significant for d-band metals, especially those with a highly enhanced χp. Numerical techniques useful for finding Fourier series representations of translationally invariant functions with cubic symmetry, important in this work, are discussed in an Appendix.
Gamma transitions in the decay of 75Se
Authors: Prasad Rajendra
Published: April 2011

Gamma transitions following the decay of 75Se have been studied using a Ge(Li) detector and a NaI(Tl)–NaI(Tl) sum-coincidence spectrometer, used in conjunction with a slow-fast coincidence circuit. Two new gamma rays of energy 373.5 and 556.4 keV have been observed and confirmed in the level scheme of 75As. Ambiguous gamma transitions of 249.2, 468.6, 542.2, and 821.6 keV energies have also been confirmed. No evidence was found for the existence of 269.0, 293.0, and 308.0 keV transitions. The accurate intensities for various transitions have been determined.
Special points for the evaluation of form factors and Fourier series representations in hexagonal crystals
Authors: Fehlner W. R. , Vosko S. H.
Published: April 2011

Efficient Gaussian type formulae are developed for evaluating the Fourier coefficients (form factors) of symmetrized plane waves for a hexagonal close-packed system in both real and reciprocal space ([Formula: see text] and [Formula: see text], respectively). These are the most efficient possible for a small number of sample points and represent a major advance over previous work on special point formulae. They will be particularly powerful for performing calculations of surface properties. The convergence of a Fourier series representation of energy bands is investigated by use of these formulae and found to converge slowly.
Influence of optimum balanced linear coma on disk spread functions
Authors: Gupta A. K. , Singh R. N. , Singh K.
Published: April 2011

Disk spread functions are evaluated to study the performance of optical systems in the presence of linear coma. Optimum balance among various coma terms based on Strehl intensity criterion is used and the applicability of this balance to imaging of extended objects is examined. Graphical results of intensity distribution in the paraxial receiving plane for the diffraction images of extended circular targets for various sizes and azimuths are presented. Results for the point spread function in presence of optimum balanced linear coma come out as a special case and are also included.
Inhomogenous diffusion equations in plasma physics and fluid dynamics
Authors: Lai C. S.
Published: April 2011

Using the method of self-similar solution of partial differential equations, analytical solutions for the two- and three-dimensional inhomogeneous diffusion equations with the diffusion coefficients D ~ rm are obtained. The solutions found can be useful in studying the diffusion characteristics of some fluids and plasmas.
Le spectre électronique de SbN dans la region 3300–4000 Å
Authors: Jenouvrier Alain , Daumont Dominique , Pascat Bernard
Published: April 2011

Ten bands of SbN shaded to the red appear in the spectra produced by a microwave discharge through SbCl5 + N2 + He or Sb + N2. We show the bands primitively ascribed to this radical are bands of Sb2.The bands of SbN are from the A1Π–X1Σ+ transition. Their rotational analysis unambiguously gives the nature of the radical by isotopic effect study. The constants of the X1Σ+ ground state are derived and the vibrational and rotational perturbations in the A1Π state are observed. Finally, a discussion on the perturbing states is proposed.
Barometric effect in low level counting
Authors: Planinić J.
Published: April 2011

The correlation between the proportional counter and the barometric pressure was examined. The barometric coefficient was estimated by means of the regression line equation and the measured background was corrected according to the standard barometric pressure.
Alpha particles from the photodisintegration of 9Be in the photon energy region 18 to 26 MeV
Authors: Buchnea A. , Johnson R. G. , McNeill K. G.
Published: April 2011

Alpha particles from the 9Be(γ,n)8Be(16.6) and 9Be(γ,α0)5He reactions were studied in the photon energy region 18 to 26 MeV; the results yielded a combined integrated cross section of 13.1 ± 2 MeV mb and an upper limit on the integrated (γ,α0) cross section of 4.0 MeV mb. This agrees within error with the integrated cross section of Becchi, Meneghetti, Sanzone, and Vitale, 10 ± 2 MeV mb, which would contain about 50% of any contribution from the (γ,α0) reaction. These reactions together with the 9Be(γ,n1)8Be reaction (which has an integrated cross section of 2.4 ± 0.4 MeV mb) are the major reaction channels contributing to the total photoneutron cross section in this energy region. Their sum, 15.5 MeV mb, agrees well with the results of Nathans and Halpern and Hughes, Sambell, Muirhead, and Spicer but disagrees with that of Costa, Pasqualini, Piragino, and Roasio.
Spin resonance in alloys of (SnTe)1−x (MnTe)x
Authors: Cochrane R. W. , Hedgcock F. T. , Lightstone A. W.
Published: April 2011

Previously published electron spin resonance data on the (SnTe)1−x(MnTe)x system indicates that the observed resonance is due to the manganese ions present in a doubly ionized S ground state with a g value of 2.00 ± 0.02. Data are presented to show that the line width is controlled above the ferromagnetic ordering temperature by the manganese ion interaction with the conduction electrons and the line area is controlled by the manganese ion magnetization. Below the ordering temperature all of the line width, line area, and central resonance field correlate with the experimentally determined magnetization. The temperature dependence of the line width and resonance field in the ferromagnetic regime is not explainable by demagnetization effects alone but require some additional relaxation channel to open below the ordering temperature.
Spectra of the d1Σ+–c1Π and d1Σ+–b1Σ+ systems and dissociation energy of NH and ND
Authors: Graham W. R. M. , Lew H.
Published: April 2011

Spectra of the d1Σ+–c1Π system of NH and ND and the d1Σ+–b1Σ+ system of NH have been observed which substantially extend previous data. The following equilibrium constants have been derived (in units of cm−1):[Formula: see text]Observation of predissociation in the c1Π state yields the following upper limits on the dissociation energy: D00 (NH) ≤ 3.47 eV and D00 (ND) ≤ 3.54 eV.
Static critical behaviors in random-spin systems with short-range interaction
Authors: Yamazaki Yoshitake
Published: April 2011

Critical behaviors in quenched random-spin systems with N-spin component are studied in the limit M → 0 of the non-random MN-component models by means of the renormalization group theory. As the static critical phenomena the stability of the fixed points is investigated and the critical exponents η[~ O(ε3); ε ≡ 4 – d], γ, α, and crossover index [Formula: see text] and the equation of state [~ O(ε)] are obtained. Within the approximation up to the order ε2, even the random-spin systems with N = 2 or 3 are unstable in the three dimensions and the pure systems are stable there.
Electromagnetic field in the nucleus and the Salam–Strathdee phase transitions
Authors: Lee H. C. , Khanna F. C.
Published: April 2011

Electromagnetic fields in the interior of the nucleus (hypernucleus) as well as inside the constituent nucleons (hyperons) are calculated. The results are discussed in the context of the Salam–Strathdee phase transition in connection with the possible vanishing of the Cabibbo angle. We show that existing data constrain the minimal range of 'normal' values for the invariant [Formula: see text] to be [Formula: see text]. Interestingly, in many Λ-hypernuclei [Formula: see text] is outside this minimal range.
Some characteristics of high energy proton–nucleus collisions
Authors: Khan A. R. , Irfan M. , Zafar M. , Ahmad S. , Ahmad I. , Ahmad Z. , Shafi M.
Published: April 2011

The variation of emission frequency, f, of fast protons, deuterons, tritons, He-nuclei, and slow pions, produced in 24 GeV/c proton interactions with Ag and Br nuclei of nuclear emulsion with [Formula: see text], [Formula: see text], [Formula: see text], and [Formula: see text] has been investigated. For all the particles [Formula: see text] has been observed to increase linearly with [Formula: see text], [Formula: see text], and [Formula: see text]. The variation of [Formula: see text] with [Formula: see text] has been found to be linear for slow pions, protons, and deuterons, whereas it varies as [Formula: see text] in the case of tritons and He-nuclei. The frequency of slow pions has been determined to be ~(0.33 ± 0.04), which is ~ 7.8% of the mean number of grey tracks. Further, the emission of low energy pions has been observed to be more frequent in relatively heavier stars.
Helium irradiations of copper at 1 to 25 keV: range profiles, reemission, and blistering
Authors: Terreault B. , St-Jacques R. G. , Veilleux G. , Martel J. G. , L'Ecuyer J. , Brassard C. , Cardinal C.
Published: April 2011

A fairly comprehensive (but by no means exhaustive) study of the effects of 1–25 keV helium ion bombardment of copper is presented. The range distributions of 1, 5, 10, 15, 20, and 25 keV ions have been measured with a resolution of 300 Å (FWHM) and compared to theory; they are wider than calculated for amorphous copper. Surface topography (blistering), gas reemission, and the helium depth profiles, under high dose bombardment (2.9 × 1017 to 18.7 × 1017 He/cm2), have been studied at 25 keV at room temperature and at 10 keV at 200 and 400 °C. The results are compared to data in other metals and analysed in terms of current models. The gas pressure model of blistering is favored over the stress model. Evidence is found for considerable swelling (60%). Surface roughness keeps increasing with dose after blistering has disappeared and surpasses the blister lid thickness.
The CW coherent anti-Stokes Raman spectrum of the ν1 band of CH4 and its pressure dependence
Authors: May A. D. , Henesian M. A. , Byer R. L.
Published: April 2011

The pressure dependence of the CW coherent anti-Stokes Raman spectrum (CARS) in the neighbourhood of the ν1 band in CH4 is examined. The observations remove the apparent disagreement between the measurements of Clements and Stoicheff and those of Boquillon, Moret-Bailly, and Chaux. A qualitative understanding of the evolution of the spectrum with density is given in terms of motional narrowing.
Infrared study of the X2Π ν = 0, 1, 2 levels of 14N16O. Preliminary results on the ν = 0, 1 levels of 14N17O, 14N18O, and 15N16O
Authors: Amiot C. , Bacis R. , Guelachvili G.
Published: April 2011

The analysis of high resolution Fourier spectra (2.5 × 10−3 cm−1) led to accurate molecular constants for the vibrational levels ν = 0, 1, 2 of the X2Π state of 14N16O and of the levels ν = 0, 1 of the X2Π state of 14N17O, 14N18O, and 15N16O. A computer program has been written to directly reduce the data. It is shown that the expected variations for the different parameters with isotope substitution are well verified. Values of AJ(e) and γe are determined and discussed.
Calculation of per-unit-volume RF scattering cross sections in the radar aurora
Authors: Minkoff J.
Published: April 2011

The interpretation of radar auroral scattering measurements is considered, with a view towards providing a consistent general basis for description and comparison of observations. A relationship is derived expressing a per-unit-volume measure of the magnitude of the electron-density fluctuations in terms of the measured scattered power. Because of uncertainty regarding the aspect sensitivity and the thickness of the scattering layer, sometimes only a lower bound can be established definitively. Numerical results based on experimental observations are presented.
Decay properties of 181Ir
Authors: Ladenbauer-Bellis I. M. , Sen P. , Bakhru H.
Published: April 2011

181Ir activity was produced via the following heavy-ion reactions: 169Tm (16O,4n)181Ir and 169Tm(19F,7n)181Pt (51 s) decaying to 181Ir. The half-life of 181Ir was found to be 4.90 ± 0.15 min. Singles and coincidence γ-ray measurements were performed using 30–40 cm3 Ge(Li) detectors. X-Ray measurements were carried out using an intrinsic Ge-detector. Additionally the helium jet system was used to study the properties of this isotope. The following γ rays were found to belong to the decay of 181Ir: 19.6, 65.3, 93.8, 107.6, 117.9, 123.5, 184.6, 189.9, 227.0, 231.6, 239.2, 309.0, 318.9, 350.5, 352.8, 375.2, 576.5, 700.1, 871.2, 1182.3, 1192.6, 1347.1, 1381.0, 1528.8, 1545.0, 1565.6, 1593.4, 1639.6, 1646.4, 1652.5, and 1714.9 keV. A tentative decay scheme is proposed for 181Ir, verifying levels in l8lOs that have been obtained by reaction work. The proposed decay scheme as well as spin and parity assignments of some of the 181Os levels are discussed.
The Huggins bands of ozone
Authors: Brand J. C. D. , Cross K. J. , Hoy A. R.
Published: April 2011

The vibrational analysis of the Huggins band system of O3 is reexamined and the electronic transition identified as 1A1 ← 1A1 on the basis that 1–0 and 0–1 transitions in ν3 are widely distributed in the spectrum. Franck–Condon analysis indicates that the 2lA1 state has r = 1.360 Å, θ = 102.4°, corresponding to a longer bond and sharper angle than the ground state structure (r0 = 1.279 Å, θ0 = 116.8°). Estimates of the upper state decay time (2 × 10−13 s) and the f-value of the transition from the ground state (~ 1 × 10−4) are presented. The upper state potential well is considered to result from the avoided crossing of the X1A1(4π) and 21A1(6π) diabatic surfaces.
A simple model for phase transitions in monolayers and bilayers of lipid molecules
Authors: Caille A. , Rapini A. , Zuckermann M. J. , Cros A. , Doniach S.
Published: April 2011

A simple model for first order phase transitions in monomolecular systems is developed and applied to (i) the condensed mesophase – liquid mesophase chain melting transition of phospholipid mono- and bilayers and (ii) a cooperative chain lifting phase transition found in monolayers of diesters with two polar heads. The excluded volume interactions are included in the model by requiring the polar heads to lie on a two-dimensional hexagonal lattice. The attractive van der Waals interactions are assumed to act between averaged molecular configurations of different surface area per polar head. Both the attractive intermolecular interaction and the description of the neighbourhood of the molecules are analyzed in the molecular field approximation. It is shown that the neighbourhood effects are negligible for the chain melting transition, which can then be described by a [Formula: see text] Ising model. They are, however, shown to be important for the chain lifting transition. The last section contains applications to experimental data and comments on the possibility of extending the model to the description of phospholipid mono- and bilayers with impurities.
Calculs et observations de nouvelles transitions dans le B IV doublement excité
Authors: To K. X. , Drouin R.
Published: April 2011

Energy levels of some doubly-excited states are computed using the atomic screening theory. Using these calculations, eight new transitions are identified in the beam-foil emission spectra of helium-like boron. Agreement between predicted wavelengths and those observed is good. Calculated results are included for further applications.
Drift mobility and Hall coefficient factor of holes in germanium and silicon
Authors: Nakagawa H. , Zukotynski S.
Published: April 2011

The drift mobility and the Hall coefficient factor are calculated using the Kane band structure model without approximations. Acoustic and optical phonon scattering and also impurity scattering are considered. The effects of light and heavy holes on the drift and the Hall mobility are discussed. The results for the drift mobility agree with experimental data both for Ge and Si. The results for the Hall coefficient factor are in good agreement for Si, but in the case of Ge, the agreement is only fair.
Double-beta decay and resonances in the nucleus
Authors: Picciotto Charles
Published: April 2011

Double-beta decay half-lives are calculated with the assumption that the emission of electron–neutrino pairs occurs via a Δ(1232) resonance in the nucleus. Numerical results are obtained with a quark model for the hadrons. By assuming that total rates are produced by a combination of neutrinoless and two-nuetrino modes, a lepton-nonconservation parameter η ~ 10−5 is obtained. Although the actual modes of decay and underlying mechanisms are undetermined, the present calculation can be used to obtain an upper limit for the probability admixture of resonances in the nucleus of a few percent.
The spin model. I. Derivation of high temperature series expansions for thermodynamic quantities
Authors: Rogiers J. , Lookman T. , Betts D. D. , Elliott C. J.
Published: April 2011

Exact high temperature series expansions have been obtained for the free energy, the fluctuation of the transverse magnetization, and the fourth order fluctuation of the transverse magnetization of the spin [Formula: see text] model through degrees 13, 12, and 9, respectively, in the inverse temperature on one, two, three, and four dimensional lattices. A new method for identifying graphs and a new theorem for calculating vertical weights have been introduced in this work.
X-Ray Raman scattering in amorphous boron
Authors: Leventouri D. K. , Vaiopoulos S. S. , Vassilikou A. B. , Koumelis C. N.
Published: April 2011

Raman scattering was measured using X-ray CrKβ radiation in amorphous boron for a scattering angle 45° and with a new type graphite spectrometer without collimators.Two energy shifts from the primary line were observed, one at a distance of 193 eV, which is ascribed to the Raman band, and the other at a distance of 183 eV, which is ascribed to the 1s–2p transition.
The two-photon laser beam as a breathing mode of the electromagnetic field
Authors: Rowe D. J.
Published: April 2011

It is predicted that the beam from a two-photon laser, if it can be made to operate in a coherent mode, will have properties quite different from the classical properties of the standard single-photon laser. Whereas the coherent beam of the single-photon laser is a dipole mode of the electromagnetic field, that of the two-photon laser is expected to be a monopole or quadrupole mode. It is predicted that the coherence properties of the two-photon laser will show up rather dramatically in non-linear processes.
Plasmons de surface autour d'une cavité située dans un métal semi-infini
Authors: Ronveaux André , Moussiaux Alain
Published: April 2011

The equations giving the proper modes of oscillation of the surface plasmons around a cavity in the interior of a semi-infinite metal are established. These modes are calculated to the lowest order for any l, m, and the dominant term in the Van der Waals interaction between the hole and the surface can be obtained from them. The method, which uses Hankel transforms, can easily be extended to the study of cavities located in a film or in a superposition of films.[Journal translation]
Possible new methods of detecting cosmic-ray electrons by their synchrotron radiation in the geomagnetic field and interstellar magnetic field
Authors: McBreen B.
Published: April 2011

New methods are suggested for distinguishing primary electrons above 1014 eV from other primaries based on their synchrotron radiation in the geomagnetic field. In addition, it is shown that the synchrotron gamma-ray emission from electrons above 5 × 1018 eV may be used to detect these electrons at distances up to 1015 m from the earth with collection areas of about 107 km2.
Anharmonic effects in the optical absorption and emission by impurities in non-metals
Authors: Chow H. C.
Published: April 2011

The effects of anharmonicity on the absorption and emission spectra of imperfections in non-metals are examined. The study is based on an approximately derived line-shape function that is appropriate to the systems, regardless of the coupling strength between the imperfection and lattice vibrations. It is shown that, primarily because of the phonon life-time effects, anharmonicity broadens the so-called zero-phonon line in a weakly coupled impurity–lattice system.
The OH Meinel bands in the airglow—the radiative lifetime
Authors: Llewellyn E. J. , Long B. H.
Published: April 2011

A model of the rotational relaxation of an emitting population has been used to determine the rotational temperature of emitted spectra for the OH Meinel bands. It is shown that the calculated rotational temperatures for these spectra are consistent with laboratory observations of the hydrogen–ozone reaction if the radiative lifetime for the Meinel bands is short, [Formula: see text]The model is also used to infer the initial rotational populations of the OH vibrational levels excited in the hydrogen–ozone reaction. It has been found that these initial rotational populations may be described by rotational temperatures of 1940, 1230, and 760 K for the seventh, eighth, and ninth vibrational levels, respectively. It is also concluded that the rate constants for vibrational quenching will be increased from previously accepted values. The effect of a short radiative lifetime for airglow observations is also discussed.
The electronic spectrum of the CS+ molecular ion: rotational analysis and perturbation effects in the A2Πi–X2Σ+ transition
Authors: Gauyacq D. , Horani M.
Published: April 2011

A new emission spectrum in the red region (6000–8000 Å) has been recorded from a low pressure hot cathode discharge through carbon disulfide. This band system has been assigned to the A2Πi–X2Σ+ transition of the CS+ molecular ion on the basis of the rotational analysis and comparison with other nine valence-electron molecules. Molecular constants have been obtained by direct least squares fits of the line frequencies to the difference of the eigenvalues of standard 2Π and 2Σ+ matrices.A local perturbation in the A2Πi (ν = 5) state has been studied quantitatively. The position of the perturbing vibrational level in the X2Σ+ state has been determined within a few centimetre−1. This study gave a consistent set of molecular constants for the ground state of CS+ and allowed a partial deperturbation treatment of the observed vibrational levels of the excited A2Πi state.Numerous bands are also observed in the 4000 Å region. A discussion is given concerning the possible assignment of bands at 4059 and 4110 Å to the CS+B2Σ+–A2Πi (0,0) transition.
Etude du pentafluorure d'iode en ondes millimétriques
Authors: Truchetet F. , Jurek R. , Chanussot J.
Published: April 2011

Pure rotational spectra of IF5 have been studied up to 210 GHz. Five molecular parameters have been determined from 318 measured lines. The assignment of these transitions has been done from spectra obtained with a video spectrometer and a source modulation spectrometer. The results are in good agreement with those known for molecules of the same family.
Radiative lifetimes and hyperfine constants for the 3d complex of molecular hydrogen
Authors: Chien C. W. T. , Dalby F. W. , Linde J. Van Der
Published: April 2011

Accurate experimental radiative lifetimes, disalignment cross sections, hyperfine constants, and Zeeman g factors are reported for a number of rotational levels of the 3d electronic complex and the nearby doubly excited K1Σg+ state of molecular hydrogen. The 3d complex of states is not a complete basis for calculation of the above molecular properties. A theory of the Hanle effect in the presence of hyperfine structure is presented.
Effect of polarizability on the vibrational and thermal properties of rare gas solids
Authors: Jain S. K. , Srivastava G. P.
Published: April 2011

A simple shell model theory has been developed for the study of lattice dynamics of monatomic crystals. The phonon dispersion curves and variations of heat capacities with temperature are reported for solidified krypton and argon. The model parameters have been evaluated using the recent experimental values of elastic constants, polarizability of atoms, and a zone boundary frequency in each case. The zero point effects are also included by expressing the zero point energy in terms of the interatomic potential. The agreement between the theoretical and experimental results is found to improve appreciably by incorporating polarizability of atoms.
Aspects théoriques des échos de polarisation pour une poudre piézoélectrique
Authors: Ettinger Henri , Lakhani Amir A. , Cheeke David
Published: April 2011

A theoretical study of the consequences of the model of Melcher and Shiren for the echosof a piezoelectric powder is presented. This model predicts most of the experimental results, but disagrees with the results of a rotation of the sample on the memory echo.
197Au and 119Sn hyperfine fields in PtMnSn
Authors: Leiper W. , MacKay G. R. , Judah J. , Blaauw C. , Rush J. D.
Published: April 2011

The 197Au and 119Sn hyperfine fields in the Heusler-type alloy PtMnSn have been measured as H(Au) = ±705 ± 12 kOe and H(Sn) = −60 ± 10 kOe, respectively, using the Mössbauer effect. The systematic trend for H(Au) in PtMnSn, Au2MnAl, and AuMnSb is discussed in terms of a local charge-screening model. The negative sign of H(Sn) is opposite to that found in two previous measurements by other workers.
Inhomogeneous thermal conduction equations
Authors: Lai C. S.
Published: April 2011

The method of self-similar solution of partial differential equations is applied to the one-, two-, and three-dimensional inhomogeneous thermal conduction equations with the thermometric conductivities χ ~ rmWn. Analytical solutions are obtained for the case that the total amount of heat is conserved. For the case that the temperature is maintained constant at r = 0, a new technique of the series solution about the point of intercept is proposed to solve the resultant nonlinear differential equations. The solutions obtained are useful in studying the thermal conduction characteristics of some incompressible fluids.
Scaling function for two-point correlations in disordered systems
Authors: Crişan M. , Dădârlat D.
Published: April 2011

We consider the two-point correlation function for the random spins system near the critical temperature expressed as G(r,q) = Cr−γD(ξ2q2), r = a(T − Tc)/Tc. The universal function D(q2ξ2) is calculated for the random system using the method applied by Fisher and Aharony for pure systems. The deviation from the Orstein–Zërnike behaviour of the universal function is found to be small because of the coefficient of the expansion. The expression of the critical index η obtained by this method has the same value as the value obtained by other authors.
Very low energy scattering in HH+ and HD+
Authors: Davis Jon P. , Thorson W. R.
Published: April 2011

Differential and total cross sections for elastic scattering and resonant–near-resonant charge exchange have been computed for H+–H(1s) and H+–D(1s) collisions in the energy range 0 to ~0.1 eV, using a rigorous quantum mechanical formulation of slow collision theory in which all spurious couplings of the perturbed stationary states (PSS) theory are removed. Orbiting and shape resonances are described and compared in the two systems, and in addition the distinctive features of the HD+ case, such as the appearance of several Feshbach resonances in the region below the D+–H(1s) threshold, are identified and discussed. Most of the effects of the isotopic H(1s)–D(1s) splitting disappear at collision energies near the end of this range.
The 12C(3He,γ0)15O reaction in the giant dipole resonance region
Authors: Bianco W. Del , Kim J. C. , Kajrys G.
Published: April 2011

The 90° differential cross section of the 12C(3He,γ0)15O reaction has been measured at 3He-particle energies from 5.24 to 13.95 MeV in steps varying from 100 to 300 keV. The γ rays have been detected by a 23 cm long × 23 cm diameter NaI(Tl) crystal spectrometer enclosed in an anticoincidence shield. The yield curve shows a resonant structure at the energies Eexc = 17.04 ± 0.06, 18.65 ± 0.06, 19.55 ± 0.08, 20.40 ± 0.07, and 21.61 ± 0.07 MeV.
Magnetic properties of amorphous CrxPd82−xGe18 alloys
Authors: Ilonca Gheorghe
Published: April 2011

Magnetoresistivity, magnetic susceptibility, and high-field magnetization measurements were done on the amorphous CrxPd82−xGe18 alloys for 1 ≤ x ≤ 8. These amorphous alloys were prepared by radio-frequency (rf) sputtering using argon gas, depositing onto fused quartz substrates to thicknesses of about 20 μm.A negative magnetoresistivity approximately proportional to the square of the magnetization and a susceptibility obeying the Curie–Weiss law for a wide temperature range were observed for these amorphous alloys with the high concentration of Cr.Also, a well-defined cusp in the magnetic susceptibility vs. temperature curve is observed for these alloys except for the case where x = 0. Such observations as the concentration range for the magnetic impurity, the cusp in the nature of the magnetic susceptibility, and negative magnetoresistivity suggest that the materials are in the spin glass region.
Optical model analysis of p + 4He elastic scattering at intermediate energies
Authors: Leung S. W-L. , Sherif H. S.
Published: April 2011

The conventional optical model potential is used to analyze the p + 4He elastic scattering data in the energy range 100–1150 MeV. Both differential cross section and polarization data are reasonably fitted. The behavior of the volume integral of the real central potential as a function of energy is studied and is found to follow the same trend observed for heavier targets. The energy dependence of the imaginary central potential is also studied. The imaginary spin–orbit term is found to be important in this energy region. In some cases, the rising backward cross section is fitted by introducing a simple real exchange potential.
Critical constants and density dependence of the Lorenz–Lorentz coefficient for germane
Authors: Palffy-Muhoray P. , Balzarini D.
Published: April 2011

The index of refraction at 6328 Å has been measured for germane in the density range 0.15 to 0.9 g/cm3. The temperature and density ranges over which measurements are made are near the coexistence curve. The coefficient in the Lorenz–Lorentz expression, [Formula: see text], is constant to within 0.5% within experimental error for the temperature range and density range studied. The coefficient is slightly higher near the critical density. The critical density is measured to be 0.503 g/cm3. The critical temperature is measured to be 38.92 °C.
A possible pomeron building mechanism in the fragmentation region
Authors: Georgalas C. G. , Papargyropoulos P. H.
Published: April 2011

By the use of a Regge parametrization of the one-particle inclusive cross section in the fragmentation region, an integral equation is obtained for the high-energy hadron–hadron inelastic cross section. The main assumptions used in the derivation of this integral equation are: (i) When two hadrons collide with sufficiently high energy, the elastic, inelastic, and total cross sections have the same energy dependence and (ii) Unitarity and factorization of Regge residues hold also for Reggeon–hadron 'amplitudes'. The solution of the integral equation, i.e., the function σinel(s) can be made constant or slowly increasing. For 'reasonable' values of all the parameters involved, it is in very good agreement with the high energy pp data.
Rydberg series of carbon disulfide converging to Ã 2Πu states of CS2+
Authors: Larzilliere M. , Damany N.
Published: April 2011

The absorption spectrum of carbon disulfide has been photographed at high resolution in the 95–112 nm spectral range. Four series consisting of six vibrational series converging to Ã 2Π3/2 and Ã 2Π1/2 states of CS2+ have been investigated. Quantum defects of these, and of other known series, are discussed.
Hexadecapolar induced absorption in solid parahydrogen
Authors: Poll J. D. , Tipping R. H.
Published: April 2011

We present a theoretical calculation of the intensities due to hexadecapolar induced absorption for the U1(0) and Q1(0) + U0(0) features and their associated phonon branches in a solid parahydrogen crystal. These results are compared with the recent experimental work of Prasad, Clouter, and Reddy and it is concluded that, within present uncertainties, the hexadecapolar mechanism accounts for the observed intensities.
The Rayleigh–Brillouin spectrum of hydrogen at high densities
Authors: May A. D. , Hubert M. , Ghaem-Maghami V.
Published: April 2011

The Rayleigh–Brillouin spectrum of light scattered from hydrogen at high densities is reported. The observations are compared with translational hydrodynamic theory and ultrasonic experiments. The range of densities includes the relaxation region and we find evidence for multiple relaxation. A mean relaxation time for normal hydrogen at 24 °C of (1.41 ± 0.06) × 10−8 s is found, in agreement with theoretical calculations.
Electron paramagnetic resonance study of Mn2+ doped Mg(ClO4)2∙6H2O
Authors: Dayal R. , Rao D. Ramachandra , Venkateswarlu Putcha
Published: April 2011

Electron paramagnetic resonance of Mn2+ doped Mg(ClO4)2∙6H2O crystals has been studied from room temperature (300 K) down to liquid nitrogen temperature at X-band. The room temperature results show three inequivalent sites for Mn2+ in the crystal. Hyperfine forbidden transitions are observed when the magnetic field is not oriented along one of the principal axes. Two structural phase transitions have been observed at temperatures of 272 ± 1 and 103 ± 1 K, respectively. The transition occurring at 272 ± 1 K has been observed for the first time. The transition occurring at 103 ± 1 K is the one detected earlier through Mössbauer studies.
On the derivation of the Pauli and van Hove master equations
Authors: Vliet K. M. van
Published: April 2011

We discuss the derivation of the Pauli master equation, based on a repeated random phase assumption, and of van Hove's result, based on an initial random phase assumption. For the former we indicate a derivation which is closer to the general approach of stochastic theory than Pauli's original method. For the van Hove result, we show that the diagonal and nondiagonal parts of the evolution operator of the Schrödinger or von Neumann equation are readily obtained by Zwanzig's projection operator method.
Adaptation à la symétrie, équivalents opératoriels et résonance magnétique
Authors: Kibler M. , Chatterjee R.
Published: April 2011

Basic quantities for symmetry adaptation are discussed in connection with molecular and solid state physics. This gives rise to a formalism whose central elements are operator equivalents adapted to a point group. Such symmetry adapted operator equivalents are defined in terms of Schwinger operators so that they cover the off-diagonal and diagonal cases. Special emphasis is put on the applications of the formalism to magnetic resonance. More specifically, it is shown how to apply the formalism to the construction, the study of the transformation properties, and the determination of the eigenstates of a generalized spin Hamiltonian. Numerous examples are given, as well as key tables relative to the chain [Formula: see text], to simplify the application of the formalism to electron paramagnetic resonance.
Stability criteria for converging shock waves
Authors: Ahlborn Boye , Fong Ken
Published: April 2011

Two simple analytical criteria are presented to determine approximately the region of (form and radial) stability for converging (shock) waves as function of the perturbation parameters amplitude Δr/R and center angle γ. By comparison with computer calculations these criteria were found to be safe approximations. The criteria may be stated using an index of refraction N = V∞/V(r) for the wave front.
Spinor interferometry by nuclear magnetic resonance
Authors: Kaiser Reinhold
Published: April 2011

The components of spinors corresponding to half integral spin value transform under rotation of the spatial coordinate system with a matrix of even dimensionality. This leads to a state function phase factor with period 4π rad in the rotation angle. A spectroscopic interference experiment to observe such phase factors is described in analogy with double-beam interferometry. The experiment is performed with the techniques of high resolution nuclear magnetic resonance spectroscopy and the rotational symmetry of composite spin [Formula: see text], 1, and [Formula: see text] particles is explored by calculation and observation. Side effects relating to inhomogeneity dephasing and relaxation are evident in the experimental recordings, but they are discussed only briefly. A relation is established between the spectroscopic interference experiment and earlier "spin tickling" experiments.
Structural study of chlorine pentafluoride in the condensed phases
Authors: Drifford M. , Rousson R. , Weulersse J. M.
Published: April 2011

Raman spectra of chlorine pentafluoride have been investigated in the condensed phases between room temperature and 4 K. X-Ray and neutron diffraction patterns were also recorded. The three solid phases previously described by nmr measurements have been characterised. Solid 1(161 K < T < 181 K) is body-centered cubic with a = 5.7 Å; its Raman spectrum is quite comparable with that of the liquid. Solid II (117 K < T < 161 K) is orthorhombic with a = 6.17 Å, b = 7.22 Å; c = 7.66 Å; according to the Raman spectra its structure seems to be similar to that of solid BrF5. The structure of solid III (T < 117 K) has not been determined; however, the vibrational spectra show that it is not very different from solid II.The analogy between the structures of the tri- and pentafluorides of chlorine and bromine is discussed.
Effective three- and four-body forces in the five nucleon system
Authors: Bevelacqua J. J.
Published: April 2011

Effective three-body forces utilized in the A = 3 and 4 systems are extended to the mass five system. The approach predicts an overestimate of the binding energies for both 5Li and 5He. An effective four-body interaction, derived from A = 4 ground state properties, is used in conjunction with this three-body force, and predicts results in agreement with experiment. The position of the first excited state is calculated to lie at 7.2 MeV excitation for both 5Li and 5He.
Pressure dependence of iodine nuclear relaxation in rubidium iodide
Authors: D'Iorio Marie , Armstrong Robin L.
Published: April 2011

The pressure-induced polymorphic phase transition at about 4 k bar in rubidium iodide was studied using nuclear magnetic resonance. The signature of the structural transition is a loss of echo intensity which presumably is due to an increase in the number of lattice defects as a result of the transition. The ratio of the spin–spin relaxation times of the iodine nuclei in the two phases is in agreement with the ratio predicted by a second moment calculation. The actual experimental values, however, are considerably smaller than the theoretical predictions signifying the migration of lattice defects. Estimates of the iodine spin–lattice relaxation time at atmospheric pressure indicate the necessity to include both an anharmonic Raman contribution and a covalency factor. The change in spin–lattice relaxation time with pressure as measured in the low pressure phase is dominated by the change in the lattice parameter. At the critical pressure the spin–lattice relaxation time decreases by a fractional amount which is approximately equal to the fractional volume change characterizing the transition. The pressure derivative of the spin–lattice relaxation time in the high pressure phase is nearly equal to that in the low pressure phase.
On the b1Σ–X3Σ transitions of SeO and AsF
Authors: Kristiansen P.
Published: April 2011

A non-linear least-squares procedure has been used to determine molecular constants for SeO and AsF from the b1Σ–X3Σ transitions. The present investigation strongly indicates that the original J-numbering based on combination differences and linear models is incorrect for some of the branches.