bluuebunny/crossref_metadata_2025 huggingface dataset:
Relativistic Hartree–Fock and model-potential ionization energies and oscillator strengths for transitions in the principal, sharp, and diffuse series of neutral rubidium and silver with allowance for core polarization
Authors: Migdałek J. , Baylis W. E.
Published: April 2011

Relativistic single-configuration Hartree–Fock computations of ionization energies and oscillator strengths for transitions in principal, sharp, and diffuse series of neutral rubidium and silver spectra have been performed both with and without allowance for core polarization and are compared with several model-potential calculations. The effect of polarization of the atomic core by the valence electron is included by introducing a polarization potential in the one-electron Hamiltonian and by employing the corresponding correction to the dipole-moment operator of the transition. The results obtained compare well with available experimental data and indicate a significant influence of core polarization on both ionization energies and oscillator strengths. The inclusion of polarization and exchange effects in the model-potential approach and the choice of free parameters is discussed.
The surface conditions for viscous displacement in a homogeneous porous medium
Authors: Spanos T. J. T.
Published: April 2011

The viscous surface conditions between two fluids are considered for fluid displacement in a homogeneous porous medium. The term viscous surface is defined here as a mathematical abstraction used to approximate the macroscopic shape of the boundary layer between two fixed saturations of displacing fluid by continuum theory. In the limit as the saturations approach each other, one then obtains a convergence of the viscous surface to a constant saturation contour. This yields a mathematical description of immiscible displacement in porous media which contains a theory of viscous fingering.
Time dependence of spin conversion in solid 13CH3D by nuclear magnetic resonance
Authors: Higinbotham J. , Wood B. M. , Code R. F.
Published: April 2011

The time dependence of the proton spin-species conversion has been observed in an annealed sample of 13CH3D containing ~0.4% oxygen impurities. At temperatures between 1.8 and 4 K, equilibrium between spin-species was obtained in less than 20 min. This time is nearly three orders of magnitude shorter than a value previously reported for the same sample at 11.4 K. The difference is ascribed to an improper establishment of orientational order in Phase III dining the original experiment. The temperature dependence of the proton second moment is also reported between 1.8 and 25 K.
The multi-fluid behaviors between an electrically stressed spherical cathode and spherical anode
Authors: Hamdi Abd-Elhamid
Published: April 2011

The effect of negative corona discharge on a background of neutral atoms has been studied. The boundary conditions at the discharging probe surface and a spherical shell located away from the probe surface were obtained. In spherical geometry, the governing differential equations were examined. It was found that the neutral particles have no mass flux with the assumption of spherical geometry. Their number density showed an exponential decay toward the probe surface. The ions' governing differential equations were reduced to one ordinary nonlinear differential equation which governs the potential distribution with a nondimensional parameter C[Formula: see text]For a wide range of probe radii (a probe radius greater than 10−6 m) and probe potentials (1–50 kV), the current was found to be small (less than 2.3 × 104 μA). and the parameter C was found to be small [Formula: see text]. Under this condition, a perturbation method of solution for the potential was constructed. The space charge effect and the shell location were found to be the contributors to the deviation from the linear potential distribution. A measure, for the condition under which the space charge effect remains a small perturbation, was obtained; this indicated that the deviation is greatly affected by the shell location. Up to a distance of 104 times the probe radius, the potential distribution was found to be nearly linear.For large probe potential, the ions' number density was found to remain nearly constant except for a thin layer near the shell surface. The thickness of this layer diminished with increasing probe potential.
Effect of ion-tail formation on the resistivity of a turbulent plasma
Authors: Jain H. C. , Sharma S. R.
Published: April 2011

Effect of ion-tail formation on the resistivity of a plasma in the presence of ion-acoustic instability has been studied. It is found that the resistivity is significantly modified due to ion-tail formation. The effect is particularly significant for higher fluctuation levels. The variation of the drift velocity, ion tail population, and resistivity as function of Ti/Te is investigated for different fluctuation levels and the results have been presented graphically. Conservation of momentum and energy is also checked.
The variation of pionic X-ray intensity with atomic number
Authors: Pearce R. M. , Beer G. A. , Dixit M. S. , Kim S. K. , Macdonald J. A. , Mason G. R. , Olin A. , SABEV C. , Sperry W. C. , Wiegand C.
Published: April 2011

Pionic X-ray intensities have been measured for 57 elemental targets. For each transition, in addition to the broad maximum as a function of Z expected from the Auger effect and the strong absorption, local intensity maxima are observed near Z values of closed atomic shells.
Canonical formulation of the free spin-2 field
Authors: McKeon Gerry
Published: April 2011

By examining the Bargmann–Wigner equations for the free spin-2 field, we arrive at the standard Fierz–Pauli equations. The Lagrangian from which these equations can be derived is then analyzed using the canonical formalism introduced by Dirac.
Lattice dynamics of sulphur dioxide using a rigid molecule model
Authors: Rastogi A. , Anderson A. , Leech J. W.
Published: April 2011

Lattice dynamics calculations on the orthorhombic crystal SO2 are presented. The model assumes rigid molecules with Lennard-Jones interactions between atoms and also electrostatic interactions between point dipoles placed on atomic centres. The oxygen atom dipoles point along the O—S bonds, and resultant molecular dipole and quadrupole moments are consistent with experimental values. The parameters of the model are optimized to give a least-squares fit to observed zone centre frequencies, equilibrium conditions, and lattice energy. It is found that small variations of the experimental lattice parameters allow significant improvement in modelling the stability of the lattice. Dispersion curves obtained for this model are shown for the principal symmetry directions.
Doppler-free two-photon absorption spectrum of rubidium
Authors: Stoicheff B. P. , Weinberger E.
Published: April 2011

Doppler-free, two-photon spectroscopy has been used to investigate the transitions n2S ← 52S and n2D ← 52S of atomic rubidium, from n = 9 to 116 and n = 7 to 124, respectively, only 7.3 cm−1 from the ionization limit. Wavelengths of these transitions have been measured to an accuracy of 1 part in 107, and series formulae computed for term values and quantum defects. Hyperfine structure splittings in the 92S to 132S levels have also been measured.
Three-body problem of two electron atoms. II
Authors: Lie S. G. , Nogami Y.
Published: April 2011

With the ansatz that the ground state wave function for a helium-like atom is of the form of [Formula: see text], the optimal correlation function [Formula: see text] is determined. Here x and y are the distances of the electrons from the nucleus, while z is that between the electrons. The parameters α and β are determined by minimizing the energy of the system. The method is particularly useful for calculating quantities which are sensitive to the short-range electron–electron correlation.
Ground based observations of stratospheric nitrogen dioxide
Authors: Syed M. Q. , Harrison A. W.
Published: April 2011

Ground based measurements of stratospheric NO2, using four different established methods based on twilight sky observations in the spectral region 437.0–451.0 nm have been made at two locations: Primrose Lake (54.78°N, 110.05°W) and at Priddis (50.86°N, 114.29°W), Alberta, Canada, during March and April 1979. The four methods differ from one another on the basis of: (a) whether or not stratospheric ozone is taken into account, (b) whether a continuous NO2 absorption spectrum or just the absorption at a few discrete wavelengths is used for analysis, and (c) the assumed altitude distribution of NO2 concentration. Two different independently developed altitude distribution models are employed in obtaining the NO2 vertical column abundance and its effective altitude from a set of slant column abundances, measured in the twilight sky at different solar zenith angles in the range 85–96°. A comparison shows that the use of one or the other of these two models alone could introduce a difference of as much as 30% in the derived vertical column abundance.
Diffraction of a plane wave by a half plane under mixed boundary conditions
Authors: Rao T. C. Kaladhar
Published: April 2011

The problem of diffraction of a plane wave by a semi-infinite half plane with mixed boundary conditions (Dirichlet condition on one face and Neumann condition on the other) is solved by a direct and rather straightforward method. The infinite series solution and the far field are in agreement with the previous solutions obtained by the Lebedev–Kontorovich transform method as expected, as the two methods are basically equivalent. An alternate representation of the infinite series solution is presented which is valid for any type of incident field including cylindrical and spherical fields. This representation facilitates easy analysis of transient problems and the special case of an incident plane unit step function on the half plane is given as an example.
The effect of collisions on the coherent scattering from strongly driven two level atoms
Authors: Zaidi H. R. , Prasad Mahendra
Published: April 2011

The existence of a coherent mode in phase with the near resonant driving field is reconsidered using the resolvent operator technique in Liouville space. A result, previously obtained from Green function technique, is rederived. It is shown that such a mode does not exist in the general case of collisional relaxation in a gas. As a result, the coherent scattering component acquires a nonzero width in the strong field region. This width depends on some non-Markovian collision parameters.
Study of the ν1 + ν3 and ν1 + ν6 infrared bands of methyl chloride
Authors: Bensari-Zizi Najate , Alamichel Claude , Guelachvili Guy
Published: April 2011

The ν1 + ν3 and ν1 + ν6 bands have been recorded with a resolution of 0.0075 cm−1 and about 2000 lines have been assigned. Classical least squares calculations (without resonance) have given standard deviations between 0.005 and 0.008 cm−1 for both bands and both isotopic species. As the molecular constants thus obtained are quite close to the expected values, the perturbations caused by a possible Fermi resonance are not really noticeable on the rotational structure.
Correlations between very low frequency chorus bursts and impulsive magnetic variations at L ~ 4.5
Authors: Kokubun S. , Hayashi K. , Oguti T. , Tsuruda K. , Machida S. , Kitamura T. , Saka O. , Watanabe T.
Published: April 2011

Coordinated observations of aurora, ULF, and VLF waves were made at 13 stations in Canada in January and February, 1980. The analysis of simultaneous ULF and VLF data obtained at Park Site (L = 4.4) revealed a close relationship between irregular magnetic pulsations and VLF emissions in the frequency range of 1.5–5 kHz. One-to-one correlations were observed between VLF chorus bursts and impulsive magnetic variations, called magnetic impulses, during sub-storms of Kp ≥ 4+ on the local morning-to-noon side. VLF chorus bursts consist of discrete risers of 0.1–0.3 s duration. It is found that magnetic impulses with a rise time of 0.5–1 s and with a duration of ~2 s coincide with the occurrence of VLF riser groups of a similar duration within ~2 s. This short time difference strongly suggests that magnetic impulses are caused by a conductivity enhancement due to electron precipitation induced by whistler mode waves.
Electron energy measurements in pulsating auroras
Authors: McEwen D. J. , Yee E. , Whalen B. A. , Yau A. W.
Published: April 2011

Electron spectra were obtained during two rocket flights into pulsating aurora from Southend, Saskatchewan. The first rocket launched at 1143:24 UT, on February 15, 1980 flew into an aurora of background intensity 275 R of N2+ 4278 Å and showing regular pulsations with about a 17 s period. Electron spectra of Maxwellian energy distributions were observed with an average E0 = 1.5 keV, rising to 1.8 keV during the pulsations. There was one-to-one correspondence between the electron energy modulation and the observed optical pulsations. The second rocket, launched at 1009:10 UT on February 23, flew into a diffuse auroral surface of intensity 800 R of N2+ 4278 Å and with somewhat irregular pulsations. The electron spectra were again of Maxwellian energy distribution with an average E0 = 1.8 keV increasing to 2.1 keV during the pulsations. The results from these flights suggest that pulsating auroras occurring in the morning sector may be quite commonly excited by low energy electrons. The optical pulsations are due to periodic increases in the energy of the electrons with the source of modulation in the vicinity of the geomagnetic equatorial plane.
Pulsating auroras in relation to proton and electron auroras
Authors: Creutzberg F. , Gattinger R. , Harris F. , Jones A. Vallance
Published: April 2011

Observations of pulsating auroras in the magnetic zenith and proton and electron auroras along the magnetic meridian were conducted from three stations covering from 58° to 71° invariant during the pulsating aurora campaign in Saskatchewan in January and February of 1980. Pulsations were observed only south of or on the southern edge of the proton precipitation region. This is in general agreement with other uncoordinated studies of proton and pulsating auroras in the late morning hours, but it also appears to be true for isolated events at other times as well.
Statistics of pulsating auroras on the basis of all-sky TV data from five stations. I. Occurrence frequency
Authors: Oguti T. , Kokubun S. , Hayashi K. , Tsuruda K. , Machida S. , Kitamura T. , Saka O. , Watanabe T.
Published: April 2011

The frequency of occurrence of pulsating auroras is statistically examined on the basis of all-sky TV data for 34 nights from five stations, in a range from 61.5 to 74.3° in geomagnetic latitude. The results are that: (1) occurrence probability of a pulsating aurora is 100% after 4 h in geomagnetic local time, (2) pulsating auroras occur in the morning hours along the auroral oval even when magnetic activity is as small as 0o ≤ Kp ≤ 1, (3) pulsating auroras occur even in the evening when Kp increases to greater than 3−, (4) drift of pulsating auroras is westward in the evening while it is eastward in the morning hours, (5) the region of pulsating auroras splits into two zones, 64 to 68° and 61 to 63° in geomagnetic latitude, after 4 h geomagnetic local time for Kp from 2o to 3−, and the splitting also appears to exist for greater Kp as evidenced by observation other than our auroral data. These results are discussed in relation to distributions of cold plasma irregularities and energetic electrons in the magnetosphere.
On the mass-independent renormalization scheme
Authors: McKeon Gerry
Published: April 2011

A calculation of the second order coefficient of the anomalous mass dimension function γm of Weinberg is made in quantum electrodynamics using the techniques of Sen and Sundaresan. The role of this quantity in perturbation theory is discussed from the point of view of the "Principle of Minimal Sensitivity" criterion of Stevenson.
Photoelastic behaviour and interionic potentials in alkali halide crystals
Authors: Shanker Jai , Verma T. S. , Cox A. , Sangster M. J. L.
Published: April 2011

In order to make a critical test of some recently developed interionic potentials based on the shell model, the photoelastic behaviour of the alkali halide crystals has been investigated. Values of the strain derivatives of the static and high-frequency dielectric constants have been calculated from sets of potentials due to Catlow et al., Sangster et al., and Sangster and Atwood. A comparison of the results obtained with available experimental photoelastic data demonstrates the superiority of the second set of potentials of Catlow et al.
Collision-induced Raman spectra and diatom polarizabilities of the rare gases – an update
Authors: Proffitt Michael H. , Keto J. W. , Frommhold Lothar
Published: April 2011

Calibrated Raman spectra of the rare gas homonuclear diatoms are obtained over a wide range of intensities, with polarizations of the incident beam parallel and perpendicular to the direction of observation. From the resulting spectra [Formula: see text], [Formula: see text], the polarized (P) and depolarized[Formula: see text] components are separated for the first time for the diatoms of 3He, Ar, Kr, and Xe. For direct comparison with the measurements, wave mechanical lineshapes are computed using models of the diatom polarizability tensor invariants as input. New empirical trace and anisotropy functions, consistent with the spectroscopic measurements, are thus obtained for the rare gases. We compare these where possible with existing measurements and ab initio computations.
Orientational and induced depolarized Rayleigh scattering of some anisotropic molecules in their liquid state
Authors: Perrot Michel , Besnard Marcel , Lascombe Jean , Bouachir Mohamed
Published: April 2011

The Rayleigh depolarized profiles of three symmetric top molecules, cyclopropane, allene, and benzene, are analysed. It is shown that these profiles cannot be interpreted assuming only orientational fluctuations but can be well reproduced, together with the [Formula: see text] profiles, assuming that they result from a weighted sum of an orientational profile and a damped oscillator profile. The former does not exhibit orientational cooperative effects at room temperature for the three molecules. The shape and intensity of the latter present some characteristics expected for a collision-induced profile.
Sn hyperfine field distributions in the Heusler alloys XMnSn and X2MnSn
Authors: Dunlap R. A. , March R. H. , Stroink G.
Published: April 2011

The 119Sn hyperfine field in the Heusler alloys Ir1.07Mn1.07Sn0.86, PtMnSn, Ni2MnSn, Co2MnSn, and Pd2MnSn has been measured using the Mössbauer effect. Hyperfine field distributions were obtained from the Mössbauer spectra via the Fourier expansion method of Window. The spectra of Ni2MnSn, Co2MnSn, and Pd2MnSn showed a well-defined value of the hyperfine field. This indicates a well-ordered structure and is consistent with previous neutron diffraction and NMR measurements on these alloys. The Ir1.07Mn1.07Sn0.86 and PtMnSn spectra, on the other hand, showed a wide distribution of fields, indicating a considerable amount of disorder. The extent and type of disorder, as indicated by X-ray diffraction measurements, are also considered.
Reply to "A remark on Moore's new method of obtaining approximate solutions of the Dirac equation"
Authors: Moore R. A. , Lee Sam
Published: April 2011

This work was written to clarify the use of a recently developed procedure to obtain approximate solutions of the one-particle Dirac equation directly and in response to a recent critique on its application to lowest order. The critique emphasized the fact that when the wave functions are determined only to zero order then a first order energy calculation contains significant errors of the order of α4, α being the fine structure constant, and a matrix element calculation error of order α2. Tomishima re-affirms that higher order solutions are required to obtain accuracy of these orders. In this work the hierarchy of equations occurring in the procedure is extended to first order and it is shown that exact solutions exist for hydrogen-like atoms. It is also shown that the energy in second order contains all of the contributions of order α4. In addition, we illustrate, in detail, that the procedure can be aplied in such a way as to isolate the individual components of the wave functions and energies as power series of α2. This analysis lays the basis for the determination of suitable numerical methods and hence for application to physical systems.
A high resolution study of A1Π–X1Σ transition of the PN molecule
Authors: Ghosh S. N. , Verma R. D. , VanderLinde J.
Published: April 2011

The emission spectrum of PN has been rephotographed at high resolution in the spectral region 2200 to 3100 Å. The bands analyzed involve ν′ = 0–10 to ν″ = 0–11 transitions of the A1Π–X1Σ+ system of which only a few of the strongest bands have previously been reported at low and medium resolution. From a rotational analysis of the spectrum, new perturbations in the ν′ = 0, 2, 3, and 7 levels of they'll have been observed. A deperturbation study of these levels as well as a previously reported perturbation in the ν′ = 1 identify the perturbing states as 3Δ perturbing A1Π, ν = 0 and 3Σ− perturbing A1Π, ν = 2 and 3; both states arising from the 1π42π37σ23π configuration. Molecular constants for the perturbing states are obtained in addition to improved molecular constants for the A1Π state.
Nuclear structure in a hierarchy of ideal spaces
Authors: Banville M. , Simard P.-A.
Published: April 2011

A new method permitting nuclear structure calculations for a system with an arbitrary number of fermions in an arbitrary number of subshells is developed through a generalization of the ideal space concept used in the boson methods. The nuclear shell problem is transcribed into a hierarchy of ideal spaces; the one-to-one correspondence between the states in each ideal space permits the generation of complete bases of antisymmetric states. The Hamiltonian matrix elements for the system are given. A generalization of the fractional parentage coefficients for such systems is obtained. The symmetries of those coefficients lead to a very important reduction in the complexity of the matrix elements.
Current–voltage characteristics of semiconductor–electrolyte junction solar cells
Authors: Guibaly F. El , Colbow K.
Published: April 2011

An improved model for the semiconductor–electrolyte solar cell is discussed. Charge transfer kinetics, surface recombination, recombination in the quasi neutral region and in the depletion region, as well as the series and shunt resistance of the cell are included in our model. It is shown that the surface transfer velocity of minority carriers across the semiconductor–electrolyte interface affects primarily the open circuit voltage, the fill factor and power conversion efficiency, and only to a lesser degree the short circuit current.As is the case with nonelectrolytic solid state solar cells, the series resistance of the electrochemical cell reduces the fill factor and the conversion efficiency, while the shunt resistance reduces the open circuit voltage of the cell in addition to reducing the fill factor and the power conversion efficiency.
Measuring the scale parameter of quantum chromodynamics at CHEER
Authors: Krauss Lawrence M.
Published: April 2011

The possibility of measuring the scale parameter of quantum chromodynamics, Λs, at CHEER is discussed. Rationale for the measurement of this quantity are given, along with a discussion of the theoretical difficulties involved. The measurement of the Q2 dependence of structure functions and their moments, and methods of measuring αs and its Q2 evolution, are discussed, and arguments are given for the advantages and disadvantages of going to high Q2 values at CHEER. It is concluded that while sensitivity to Λ is lowered at high Q2, CHEER will, in principle, be able to provide the first clean measurements of Λ, free from almost all the theoretical confusion involved in interpretations of present data.
An injection system for CHEER
Authors: Edwards K. W. , Johnson D. E. , Mills F. E. , Skuja A.
Published: April 2011

The injection system for CHEER must provide 34 bunches of 1011 electrons. We describe here a system consisting of a linear accelerator, accumulator–buncher ring, and a booster ring which can inject such bunches at 2 GeV into the main CHEER ring in an acceptably short time.
A new ion-pair state of diatomic iodine
Authors: Brand J. C. D. , Hoy A. R.
Published: April 2011

Transitions combining the [Formula: see text] state of diatomic iodine with a new ion-pair state designated [Formula: see text] have been observed using Doppler-limited polarization-labelling spectroscopy. A number of vibration – rotation states of [Formula: see text] have been measured and the following vibration and vib-rotational constants determined: Te = 47 027.63(18), ωe = 103.904(18), ωexe = 0.1988(5), Be = 0.020780(14), αe = 5.48(6) × 10−5 and D = 3.5(4) × 10−9cm−1. These constants were derived for f state levels with v = 13 – 25.
The magnetic rotation spectrum of thioformaldehyde: singlet–triplet perturbations in the Ã1A2 state
Authors: Clouthier D. J. , Moule D. C. , Ramsay D. A. , Birss F. W.
Published: April 2011

Singlet–triplet perturbations in the [Formula: see text] and [Formula: see text] bands of the [Formula: see text], system of H2CS have been studied by high resolution absorption and magnetic rotation spectroscopy. Extensive perturbations in the [Formula: see text] band are associated with corresponding activity in the magnetic rotation spectrum. The shifts of the levels are consistent with interaction matrix elements up to ~ 1 cm−1. The selection rules indicate that the zeroth vibrational level of the 1A2 state is perturbed by the 4361 level of the 3A2 state. A number of perturbations are also observed in the [Formula: see text] band.
Intensités des raies d'absorption des bandes perturbées ν4 et 3ν6 de 12CH335Cl
Authors: Dang-Nhu M. , Morillon-Chapey M. , Graner G. , Guelachvili G.
Published: April 2011

Strengths of individual lines of the ν4 and 3ν6 bands of methyl chloride at 3.3 μm have been measured using a high resolution Fourier transform interferometer. From these measurements we were able to deduce two significant intensity parameters, namely the unperturbed band strength of the ν4 band, [Formula: see text] at 296.35 K and the coefficient β1 = −0.0018 ± 0.0009 of the Herman–Wallis term F = [1 + ε(ν4, J, K, J + ΔJ, K + ΔK)]2 = (1 + β1m + … )2
Turbulent heating studies on STOR-I
Authors: Boucher C. , Hirose A. , Kuwahara H. , Morton A. H. , Skarsgard H. M. , Watanabe Y. , Wolfe S.
Published: April 2011

Efficient electron and ion heating is observed in a toroidal turbulent heating device, STOR-I. Energy balance and preferentially inward thermal transport are confirmed.
Superluminal coordinate transformations: the two-dimensional case
Authors: Marchildon Louis , Antippa Adel F. , Everett Allen E.
Published: April 2011

This is the first part of a two-paper series, in which we critically examine the various proposals that have been made for superluminal coordinate transformations. Here we consider the two-dimensional case. Starting from rather general assumptions, we show that the superluminal coordinate transformations in two dimensions are essentially uniquely determined. Different proposals for such transformations are then analyzed from the point of view of those assumptions. The relationship between the superluminal transformations and the discrete symmetries P (parity), T (time reversal), and PT is also discussed.
A two-step potential for quarkonium
Authors: Galic H.
Published: April 2011

A specific two-step potential, a combination of the Coulomb and linear part, is reexamined. A set of parameters is found which give a good description of the charmonium and bottonium families. Some comments are made that might be useful in further study of quarkonium systems.
Rotational cooling of aniline in axis-symmetric and planar pulsed supersonic expansions
Authors: Amirav A. , Even U. , Jortner J. , Birss F. W. , Ramsay D. A.
Published: April 2011

Laser-induced fluorescence (LIF) has been used to measure rotational temperatures, TR, of the aniline molecule in axis-symmetric and planar pulsed supersonic expansions of He, Ne, and Ar. The rotational contours of the O–O band of the 1B2 ← 1A1 transition of aniline were measured by LIF and were fitted by computer-simulated rotational contours, resulting in the determination of TR. For axis-symmetric jets expanded from a 0.06 cm nozzle at stagnation pressures p = 100–2300 Torr, we find TR to vary from 15 ± 2 K to 2.2 ± 0.2 K. The degree of rotational cooling increases in the order of [Formula: see text]. The pressure dependence of [Formula: see text] for Ar (in the range p = 100–1000 Torr) and [Formula: see text] for He (in the range p = 300–2300 Torr), manifesting the implications of the velocity slip effect. Evidence for extensive formation of van der Waals complexes in the aniline–Ar system at p ≥ 1000 Torr was inferred from the saturation of TR with increasing p in this range. In planar supersonic jets of Ar expanded from a 0.2 × 35 mm nozzle slit at p = 5–200 Torr, the rotational temperature varied in the range TR = 90 ± 10 K to 12 ± 2 K, exhibiting the dependence [Formula: see text] Additional diagnostic information on planar jets was obtained for the dependence of the rotational temperature on the distance from the nozzle slit.
Kinetics of bound excitons and multi-exciton complexes in Si(B)
Authors: Sullivan Brian T. , Parsons R. R.
Published: April 2011

The kinetics of the free exciton (FE), bound exciton (BE), and multi-exciton complexes (BMEC) have been investigated for Si(B) by using rate equations to analyze the experimental transient responses of these luminescent species. From this analysis, the B capture cross section for an exciton to bind upon a neutral impurity has been determined, as well as the B capture cross section ratios for higher order complexes. Furthermore, the lifetimes for the BE, BMEC-2, and BMEC-3 have been determined.
Phonon linewidths and line-shapes from Brillouin spectra
Authors: Vanderwal J. J. , Walton D.
Published: April 2011

A multipassed Fabry–Perot interferometer has been used to determine phonon linewidths. The line-shapes may also be obtained using a Bayesian deconvolution technique. Results on amorphous silica and CN− doped KCl are presented as illustrations.
Quelques particularités de la théorie de l'indice effectif dans les guides fortement périodiques
Authors: Verly Pierre , Tremblay Réal , Lit John W. Y.
Published: April 2011

We show that the accuracy of the effective index theory, in strongly periodical media, is strongly dependent on the shape of the grating. When proper conditions are met, this theory provides excellent results, in a very simple way.
Positron motion in metals
Authors: Kubica P. , Stewart A. T.
Published: April 2011

Positron motion has been observed in potassium, sodium, magnesium, and aluminum over a wide range of temperatures. The observations show that positrons are close to thermal equilibrium before annihilation even at liquid helium temperature. If a Gaussian momentum distribution is fitted to the data, it yields a positron apparent mass m*/m of 1.6 ± 0.1 in K, 1.55 ± 0.1 in Na, 1.2 ± 0.1 in Mg, and 1.3 ± 0.1 in Al. These new results are fairly close to the theoretical expectations, but show that the subject is not yet fully understood.
Evaluation of the internal field produced by longitudinal optic phonons in ZnSe crystals
Authors: Daunay J. , Daunay Jac. , Bugnet P.
Published: April 2011

Measurements of light absorption on ZnSe single crystals, conducted from 80 K to room temperature, show that the forbidden band gap decreases with increasing temperature because of the electron–phonon interaction. It is established for temperatures ranging from 140 to 320 K that longitudinal optic (LO) and acoustic (A) phonons operate simultaneously and exclusively so that [Formula: see text]. The first term, resulting from the Franz–Keldysh effect applied to the mean square field produced by LO phonons, provides the value of this field. It reaches 105 V cm−1 at room temperature.
The structure factor and compressibility of simple liquids
Authors: Datta S. K.
Published: April 2011

Closed analytical expressions for the structure factor of simple monatomic liquids have been obtained using the double Yukawa potential function in the random phase approximation (RPA) together with the Weeks, Chandler, and Andersen (WCA) criterion for the division of the pair potential. Isothermal compressibility of liquids have been derived in the extended random phase approximation (ERPA). The results for the structure factor and compressibility are found to be in excellent agreement with experimental data. Compressibility values in the RPA and ERPA are almost identical, indicating that the ERPA does not represent any significant improvement over the RPA, at least for this particular long wave property.
Dielectric loss at microwave frequencies of some aromatic and aliphatic aldehydes in solution
Authors: Grosse C. , Mechetti M. , Brito P.
Published: April 2011

Dielectric loss measurements on some aromatic and aliphatic aldehydes in solution were made. The microwave frequency range was 10–260 GHz and the polar solutes were dissolved at very low concentration in cyclohexane. The mean relaxation times were determined and a resolution was attempted. For substances whose molecules have a relatively rigid main body, the experimental data could be fitted using two relaxation times. For nonrigid chain molecules, the continuous Fröhlich distribution was necessary.
The microwave and millimetre wave spectrum of diazirine, H2CN2: Rotational and hyperfine structure analysis
Authors: Bogey Marcel , Winnewisser Manfred , Christiansen JØrn Johs.
Published: April 2011

The rotational spectrum of diazirine, the most stable cyclic isomer of diazomethane, has been measured in the microwave and millimetre wave ranges up to 400 GHz. The a-type R- and Q-branch lines have been assigned in the ground vibrational state and a centrifugal distortion analysis is presented.To study the hyperfine structure induced by the two nitrogen nuclei, it was necessary to take into account the spin-rotation interaction as well as the nuclear quadrupole interaction to reproduce correctly the experimental spectra. The deduced hyperfine constants are given.
Bond-length alternation and vibrational spectra of polyacetylene
Authors: Takahashi M. , Paldus J.
Published: April 2011

The effect of bond-length alternation on the main features of the Raman vibrational spectra of polyacetylene is examined. It is shown that the semiempirical potential energy surfaces for cyclic polyene models, which display the bond-length alternating equilibrium geometry, yield vibrational frequencies that are in reasonable agreement with observed principal Raman bands. However, these frequencies are rather insensitive to the details of the potential energy surface employed, thus explaining the controversy between earlier computations (Ovchinnikov et al.) and the experimental evidence of bond-length alternation in all-trans polyacetylene (Fincher, Jr., et al.). Nevertheless, the normal mode character of these vibrations qualitatively changes with the introduction of the bond-length alternation.
Vibration–rotation interaction constants and the cubic potential function of the NO2 molecule in the small-amplitude approximation
Authors: Morino Yonezo , Tanimoto Mitsutoshi
Published: April 2011

Vibration–rotation interaction constants and cubic potential constants were calculated in the small-amplitude approximation. The standard deviations of the rotational constants previously obtained by the microwave measurement were critically examined and found to depend strongly on the centrifugal distortion constants of the infrared data. Although the Coriolis interactions were all neglected, the α and γ constants thus obtained, together with the cubic potential constants, indicate no abnormal feature, in comparison with those of the ordinary triatomic molecules already studied.
High-resolution laser spectroscopy on the A3Π ← X3Σ− transition of NH
Authors: Ubachs W. , Meulen J. J. ter , Dymanus A.
Published: April 2011

In a molecular beam, laser-induced fluorescence experiment, rotational spectra of the A3Π, ν = 0 ← X3Σ−, ν = 0 transition of the NH free radical were measured at 336 nm with high resolution. From more than 300 completely resolved hyperfine lines, the hyperfine structure of the A3Π excited state and the X3Σ− ground state could be analyzed. For the first time, the hyperfine coupling constants aN.H, bN.H, cN.H, dN.H, eQq1, and eQq2 in the A3Π state were determined. Also, the nuclear quadrupole coupling constant eQq1 in the X3Σ− ground state was obtained.
Frequency selective excitation spectroscopy of the CO intercombination bands
Authors: Klopotek P. , Vidal C. R.
Published: April 2011

Using the method of frequency selective excitation spectroscopy, several bands of different intercombination systems of the CO molecule have been analyzed and measured. Using conventional methods, such as absorption spectroscopy, these bands could not be observed before owing to a severe overlap with the allowed bands of the A1Π–X1Σ+ system.
Infrared spectrum of HNCO between 8 and 80 cm−1
Authors: Fusina L. , Carlotti M. , Carli B.
Published: April 2011

The infrared spectrum of isocyanic acid, HNCO, has been recorded in the range 8–80 cm−1 with a resolution of about 0.004 cm−1a-type and b-type rotational transitions have been measured and assigned in the ground state and in the ν4 = 1, ν5 = 1, ν6 = 1, and ν5 = 2 vibrational states.Improved values of the ground state rotational and centrifugal distortion constants in the Ir S-reduced Hamiltonian of Watson have been obtained in a simultaneous analysis of our measurements and microwave, millimetre-wave, and far infrared data reported previously. Sub-band origins and effective spectroscopic constants have been determined for each excited vibrational state. An accurate value for the ν6 band origin, at 656.287 cm−1, has been deduced.
Rotational analysis of the BaI C2Π–X2Σ+ (0,0) band
Authors: Johnson Mark A. , Noda Chifuru , McKillop John S. , Zare Richard N.
Published: April 2011

Rotational analysis of the BaI C2Π–X2Σ+ (0,0) band system has been performed using molecular beam and laser spectroscopic techniques. This band is free from local perturbations, although significant interaction of the C2Π state with several other 2Σ+ states is indicated. The spin-orbit ordering of the C state is confirmed to be regular, while the Λ-doubling parameters p and q are opposite in sign. Apparent anomalies in the line strengths of various rotational branches in the two spin-orbit sub-bands are related to observed differences in the hyperfine structure of the C-state spin-orbit components.
Spin-orbit splittings and rotational constants for vibrationally excited levels of NCO(X2Πi)
Authors: Copeland Richard A. , Crosley David R.
Published: April 2011

Laser-induced fluorescence excitation spectra at 0.3-cm−1 resolution have been–obtained for the A2Σ+–X2Πi system of NCO present in an atmospheric pressure CH4–N2O flame. This combination of selectively detected laser fluorescence and a flame environment has permitted the high-resolution investigation of levels inaccessible in conventional room temperature experiments. Spin-orbit splittings, and rotational and vibrational constants have been determined for eight vibrational levels having K = ν2 + 1, and for the 010 2Σ and the 020 2Π levels, primarily by fits to band-head positions using previously determined A2Σ+constants. The results are in good agreement with theoretical predictions of Renner–Teller interactions. Fermi resonance with an interaction strength of 10 cm−1 describes variations in spin–orbit splittings and rotational constants for four levels with ν1 = 1 quite well.
The emission spectrum of ReO between 375 and 875 nm: A classification based on rotational analysis and Re16O/Re18O isotope shifts
Authors: Balfour Walter J. , Ram Ram. S.
Published: April 2011

The emission spectrum of the ReO molecule has been photographed under high resolution between 375 and 875 nm. In addition to the 711.9 and 404.5 nm systems previously studied a large number of new electronic transitions have been classified on the basis of Re16O/Re18O isotopic shifts. The rotational structures of 18 bands of Re16O and 1 band of Re18O have been analyzed. Two low-lying electronic states in addition to the known common lower state of the 711.9 and 404.5 nm systems have been identified.
Laser-excited fluorescence of the (2) double-minimum state of Na2 studied by Fourier transform spectrometry
Authors: Cooper D. L. , Barrow R. F. , Vergès J. , Effantin C. , d'Incan J.
Published: April 2011

High-resolution Fourier transform spectrometry has been used to record laser-excited fluorescence of the Na2 molecule in the infrared between 3500 and 10 000 cm−1. This has led to the characterization of a new, double-minimum, state (2) [Formula: see text] Levels of the inner potential of this state are probed by direct excitation by ultraviolet lines of krypton-ion and argon-ion lasers, while levels of the outer well and levels above the potential maximum are identified in two-photon transitions excited by a ring dye laser:[Formula: see text]Five vibrational levels of the inner well, all of the 29 levels of the outer well, and some 65 upper levels have been observed and used to construct an adiabatic potential. Constants are as follows:[Formula: see text]
Quenching of the O2 (Aν=2 → Xν=5) Herzberg I band by O2(a) and O
Authors: Kenner R. D. , Ogryzlo E. A.
Published: April 2011

Data are presented that indicate that O2(a1Δg) is an effective quencher of [Formula: see text]. In a system where O and O2 are produced by an electrical discharge in a fast-flow system, O2(A) molecules were formed by allowing some of the oxygen atoms to recombine on a nickel surface. From the decay of O2(A) in the presence of O2(a), a rate constant of (8.1 ± 3) × 10−11 cm3 molec−1 s−1 was obtained for the interaction of these two species. A revised value of 1.3 × 10−11 cm3 molec−1 s−1 for the rate constant for the O2(A)ν = 2 quenching by O has been determined. The relative quenching rate of vibrational levels 0–4 have also been estimated.
Rotational spectrum of HD at low pressures
Authors: Essenwanger P. , Gush H. P.
Published: April 2011

The pure rotational absorption spectrum of gaseous hydrogen deuteride in the pressure range 3–500 Torr has been observed using a diode laser spectrometer. The measured frequencies of the three lines studied, R(3), R(5), and R(6), equal respectively 350.852 ± 0.002, 514.656 ± 0.001. and 591.9327 ± 0.0003 cm−1. The electric dipole transition moment deduced from the intensities of the R(3), R(5), and R(6) lines equal 8.47 ± 0.09, 8.1 ± 0.8, and 9.9 ± 0.3 × 10−4 D, respectively.
Observation of the ν1 fundamental band of D2H+
Authors: Lubic Karen G. , Amano T.
Published: April 2011

The ν1 fundamental band of D2H+ has been observed in absorption between 2640 and 2990 cm−1 using a tunable difference frequency system in conjunction with a multitraversal cell. The D2H+ was generated in a modulated direct current discharge in a mixture of H2 and D2 cooled to 77 K. Thirty-five b-type transition frequencies were fitted to an effective Hamiltonian to determine the rotational constants and the band origin.
The spectrum of natural hydrogen sulfide between 2150 and 2950 cm−1
Authors: Lechuga-Fossat L. , Flaud J.-M. , Camy-Peyret C. , Johns J. W. C.
Published: April 2011

Spectra of hydrogen sulfide have been recorded between 2150 and 2950 cm−1 with a Fourier transform spectrophotometer at a resolution of 0.01 cm−1. Most of the absorption in this region is due to the 2ν2, ν1, and ν3 bands of H232S, H233S, and H234S observed in natural abundance. A careful analysis of the spectra, combined with recent data on the ground states of the three isotopic species, led to an improved and extended set of rotational energy levels of the (020), (100), and (001) vibrational states of these isotopes. The rovibrational levels have been subjected to a least squares fit, using a Hamiltonian which takes the effects of Coriolis resonance explicitly into account, and precise rotational and coupling parameters have been determined.About 529 individual line intensities have been measured and from them it has been possible to deduce the expansion of the transformed transition moment operators of the three bands 2ν2, ν1, and ν3 and to determine the first derivatives of the dipole moment[Formula: see text]Finally, a complete list of line positions and intensities of natural hydrogen sulfide has been computed which should be of interest for the analysis of infrared spectra of the giant planets and for pollution studies.
X-ray spectra of Ne-like Ba, La, Ce, and Pr ions
Authors: Aglitsky E. V. , Antsiferov P. S. , Mandelstam S. L. , Panin A. M.
Published: April 2011

The spectra of Ne-like ions of Ba, La, Ce, and Pr in the 1.9 – 2.7 Å region, excited in the low-inductance vacuum spark plasma, have been obtained for the first time. A Johann's crystal spectrograph in combination with an image intensifier was used for recording the spectra. The 2s22p6 – 2s2p63p and 2s22p6 – 2s22p53d transitions have been identified in these ions along with the satellite lines of Na-like and Mg-like Ba–Pr ions.
Ab initio studies on the oscillator strength of the spin-forbidden transition in Cl2
Authors: Grein Friedrich , Peyerimhoff Sigrid D. , Buenker Robert J.
Published: April 2011

A relatively strong absorption corresponding to the spin-forbidden transition [Formula: see text] of Cl2 had been observed earlier. Ab initio spin-orbit studies at the ground state equilibrium distance were performed, allowing for the coupling of all excited states up to 90 000 cm−1.It was found that only 21Πu couples with 23Πu to any significant extent. The oscillator strength for [Formula: see text] is calculated to be 0.0084, a factor of 8.3 smaller than the oscillator strength for [Formula: see text].
Excitation spectra for the V configuration of a three-level atom in resonance with two laser fields
Authors: Hutchinson D. A.
Published: April 2011

The excitation spectrum is calculated for a three-level atom interacting with two strong electromagnetic fields. The two fields are in resonance with the atomic transition frequencies from the ground state to the two excited states. The excitation spectrum consists of a central peak and two pairs of side bands for each of the two transitions. If the decay rates of the two excited states are equal a relatively simple closed form expression is derived for the excitation spectrum. For unequal decay rates numerical methods are used to determine the excitation spectrum for selected special cases.
Corrélation entre possibilité d'effet laser et force oscillatrice de la transition fluorescente : cas des sels de pyrylium
Authors: Rullière Claude , Declemy Alain , Balaban Alexandru T.
Published: April 2011

Laser action is demonstrated to occur in seven pyrylium salts between 4100 and 5100 Å with quantum yields extending from 4% to 12%. Theoretical calculations of the energy and oscillator strength of S0 → Sn transitions confirm band assignments deduced from experimental results. These results allow detection of a weak hidden transition in the 2,6-dimethyl-4-phenyl-pyrylium cation where laser action is not observed. This shows how important the magnitude of the oscillator strength of the first transition S0 → S1 is in selecting candidates to laser action. [Traduit par le journal]