bluuebunny/crossref_metadata_2025 huggingface dataset:
High resolution absorption spectrum of nitric oxide (NO) in the region of the first ionization limit
Authors: Miescher E.
Published: April 2011

The absorption spectrum of cold NO gas has been photographed at high resolution between 1400 and 1250 Å for two isotopic species. Resolved bands of the Rydberg series converging to vibrational levels of the 1Σ+ ground state of NO+ are studied. They include nf–X bands up to n = 15 and ns–X bands up to n = 11, all of which show sharp rotational structure. The higher members of the np–X series are generally very diffuse with only npσ being sufficiently sharp to show broadened rotational lines. Also mostly diffuse are the ndδ–X bands. The bands ndσ, π–X are not observed. The rapidly (n−3) narrowing structure of the nf complexes is discussed and the ionization energy [Formula: see text] accurately determined by extrapolation of selected rotational lines. Interactions between Rydberg states are numerous, s ~ d mixing produces a strong effect above n = 6 when (n + 1)s levels fuse with nl levels into 'supercomplexes'. Matrix elements are given for observed 8f ~ 9s and 6f ~ 6dδ interactions.Valence levels are not observed above the ionization energy, except for the repulsive state A′2Σ+ arising from the first dissociation limit and seemingly assuming Rydberg character at molecular internuclear distance. Observed anomalies are qualitatively discussed.
Quantitative spectroscopy of the aurora. IV. The spectrum of medium intensity aurora between 8800 Å and 11 400 Å
Authors: Jones A. Vallance , Gattinger R. L.
Published: April 2011

An averaged spectrum of medium intensity aurora (I(4278 Å) ≈ 20 kR) at a resolution of 15 Å from 8800 Å to 11 400 Å is presented. The observations were made with a grating spectrometer and S1 photomultiplier detector. Synthetic comparison spectra were prepared to aid in the identification and relative intensity measurements of the observed emission features. Included in the synthesis were the nitrogen first positive, Meinel, and infrared afterglow systems, the oxygen atmospheric system, the hydroxyl vibration–rotation system, and a number of atomic emissions. Three unidentified features have been tentatively ascribed to NI multiplets. Comparisons have been made between the observed and theoretically calculated relative populations of the four lowest vibrational levels in the upper electronic states of both the nitrogen first positive and Meinel systems. The relative vibrational populations of N2(B3Π) do not fit the hypothesis of direct electron impact excitation plus cascade through the N2 second positive system. The relative vibrational population rates of the Meinel N2+ system deviate from the Franck–Condon factors for the excitation transition.
A new satellite in the L-X-ray emission spectrum of erbium-68
Authors: Nigam Anand N. , Mathur Rakesh B.
Published: April 2011

Using a 40 cm curved mica crystal spectrograph of the transmission (Cauchois) type, a new satellite Lα5 at λ = 1769.0 xu has been reported for the first time in the L emission spectrum of erbium. On the basis of Wentzel's multiple ionization theory, the satellite has been assigned to the transition L3M1 → M1M5. The presence of the satellites αx, β1′, β2I, and γ1′, reported by earlier workers, has been confirmed. The assignment of the transitions to these satellites by Nigam et al. has been critically examined and finally these have been assigned to the transitions L3M2 → M2M5, L2M1 → M1M4, L3M5 → M5N5, and L2M4 → M4N4 respectively.
Delta function terms in a non-relativistic hyperfine calculation for the hydrogen atom
Authors: Moss R. E. , Watson J. K. G.
Published: April 2011

An inconsistency previously found between the relativistic and non-relativistic second-order hyperfine energies of the hydrogen atom with a point nucleus is ascribed to the neglect of delta function contributions in the non-relativistic calculation. Various relations involving point delta functions are developed. In particular, a novel representation of the commutator of partial differential operators acting on a homogeneous function of degree −n + 2 in n variables is given in terms of the point delta function. With the inclusion of the delta function terms, the non-relativistic point-nucleus result is shown to be consistent with the results of both relativistic point-nucleus and non-relativistic finite-nucleus calculations.
Surface modes of vibrations of a CsCl slab with two (110) free surfaces on the shell model
Authors: Lakshmi G. , Srinivasan R.
Published: April 2011

The surface modes of vibrations of a fifteen-layer CsCl slab using the shell model have been calculated. Results with special reference to the instability of acoustic modes are discussed.
Dipolar relaxation of several spin systems in solids
Authors: Blicharski J. S.
Published: April 2011

The relaxation of the nuclear dipolar energy of several spin systems is considered. Expressions for the dipolar relaxation time T1D are derived in the weak collision case for systems of n identical spins with I = ½, where n = 2, 3, 4, 5, and 6.
Elastic and inelastic scattering of 30 MeV polarized protons from 90Zr, 92Zr, and 92Mo
Authors: de Swiniarski R. , Pham Dinh-Lien , Bagieu G.
Published: April 2011

Analyzing powers and cross sections have been measured for elastic and inelastic scattering of 30 MeV polarized protons from 90Zr, 92Zr, and 92Mo. The experimental results are analyzed in terms of the coupled-channels formalism using the vibrational model. The best fits for the analyzing power for all the nuclei are obtained by using the full Thomas form for the spin–orbit potential. These calculations give a very good description for both the cross sections and the analyzing powers of the low-lying 2+, 3−, 5−, and 4+ states in 90Zr, 92Zr, and 92Mo. Only a small increase of the spin–orbit deformation over the central deformation (βLS/βcentral = 1.5) is needed to reproduce the data; this is contrary to the situation at lower energy where a large increase of this ratio was required (Raynal). Some differences between the 90Zr–92Mo data (which are similar) and the 92Zr data have also been observed; this is, however, in agreement with previous results at lower energy. Microscopic model calculations with tensor and spin–orbit components included in the projectile–target interaction (real interaction), and with an exact treatment of 'knock-on' exchange, have also been performed for the 2+ states in these nuclei. These calculations give a very good agreement with the cross sections but a rather poor agreement with the analyzing powers even when a complex interaction is used.
Electromigration in metals
Authors: Pai S. T. , Marton J. P.
Published: April 2011

In bulk and thin film metal samples, a net migration of material may take place when electrical current is passed through the sample at an elevated temperature. The migration is due to the passage of electron (or hole) current, the electrostatic force on the metal ions, and the temperature gradient in the sample. The extent and the direction of net migration has not been predicted satisfactorily by existing theories, leaving many unexplained anomalous experimental results. The present work is the development of a generalized theory that contains the main features of previous theories. It can explain all major experimental observations. Its main features include predictions on the temperature and time dependence of migration, its direction, its reversal temperature, and the approximate sample position that is affected most. The theory has been used to interpret available experimental data on a number of electron- and hole-type metals.
Two-particle distribution pp → pp + X and the Pomeron–Pomeron total cross section
Authors: Buchl R. A. , Nigam B. P.
Published: April 2011

A spin-averaged two-particle distribution cross section for the process pp → pp + X is derived. The triple-Pomeranchukon couplings gp(t1) and gp(t2) enter as factors in the distribution. From a colliding-beam viewpoint, the two exchanged Pomerons, with masses (−t1)1/2 and (−t2)1/2, and described by trajectories αp(t1) and αp(t2), respectively, annihilate each other to form the hadron system. The distribution exhibits factorization into a pair of one-particle distributions. A t-dependent expression is given for the triple-Pomeron coupling which allows an estimate of the Pomeron–Pomeron total cross section.
Effets d'une zone d'accumulation sur la photoconductivité du GaSb
Authors: Filion A. , Nérou J. P. , Girard P. E.
Published: April 2011

The photoconductivity of p-type GaSb is strongly influenced by surface treatment. After etching, an accumulation layer forms near the surface and the photocurrent is enhanced. The variations of the photocurrent with wavelength and incident intensity and some lifetime measurements have shown that the surface accumulation layer increases the quantum efficiency by three orders of magnitude. Furthermore, the quantum efficiency varies with penetration depth, in etched samples, being maximum near the surface. This behaviour is responsible for an oscillatory photoconductivity of GaSb in a magnetic field observed previously. Finally, slow variations explained by the presence of surface traps are also believed to be responsible for saturation effects with light intensity.
Calculation of self-broadened widths of rotational Raman lines in H2 and N2
Authors: Srivastava R. P. , Zaidi H. R.
Published: April 2011

Self-broadened widths of rotational Raman lines of S-branch in H2 and N2 are calculated in the impact and straight classical path approximation. A core potential of the form r−n is considered along with the quadrupole–quadrapole interaction. It is found that the results are sensitive to the core potential parameters. Comparison with experimental data yields values for these parameters.
Crystal fields and the Kondo effect in dilute cerium alloys
Authors: Harris R. , Zuckermann M. J.
Published: April 2011

We give simple expressions for the low temperature susceptibility of cubic and hexagonal Kondo alloys containing cerium as the magnetic impurity. We fit our expressions to data for cubic La-Ce and cubic (La-Ce)Al2, and to measurements of the parallel susceptibility in hexagonal Y-Ce.
Sea level muon spectrum derived from the Goddard Space Flight Centre measured nucleon spectrum using the Cocconi–Koester–Perkins model
Authors: Sarkar Kalpana , Bhattacharyya D. P. , Basu D.
Published: April 2011

The sea level muon spectrum is estimated from the Goddard Space Flight Centre group measured nucleon spectrum by using the model of Cocconi, Koester, and Perkins (CKP). The derived muon spectrum agrees well with the magnetic spectrograph data of Ayre, Baxendale, Hume, Nandi, Thompson, and Whalley when the energy dependence of pion inelasticity (Kπ) in the CKP model is assumed in the pion energy range 10–500 GeV. Above 50 GeV pion energy (Eπ) the pion inelasticity follows the relation Kπ = 0.1 ln Eπ.
Ferromagnetic resonance absorption in Supermalloy at 9, 24, and 38 GHz
Authors: Heinrich B. , Cochran J. F. , Baartman R.
Published: April 2011

FMR absorption lineshapes have been measured in detail at 24 GHz and at 1 °C, using a novel bolometric technique, for four specimens of Supermalloy which were also used in 24 GHz FMAR experiments. Line positions and linewidths have also been measured at 9 and 38 GHz. The purpose of these experiments was to determine the exchange constant A and the surface anisotropy parameter Ks. The results of the FMR studies were clouded by variations of a few oersteds in linewidths and in line positions from specimen to specimen due, most probably, to surface irregularities. The smoothest specimen gave the narrowest linewidths, and the lineshape for the parallel configuration at 24 GHz (dc field in the specimen plane) could be well described by values of g, Ms, and λ obtained from transmission experiments, and using A = 1.0 × 10−6 erg/cm, a surface pinning parameter K = −0.122 erg/cm2 corresponding to a uniaxial surface energy anisotropy with the easy axis along the specimen normal, and no spin-diffusion damping. The asymmetries of the 24 GHz lineshapes in the perpendicular configuration (dc field normal to the specimen plane) were not well described by the theory.
Saturation characteristics of SF6 absorption at the 10.4 μm band of CO2
Authors: Garside B. K. , Taylor R. S. , Ballik E. A.
Published: April 2011

Measurements were made of the saturation characteristics of the SF6 absorption at the 10.4 μm band of CO2, using a pulsed CO2 laser. It is shown that the observed nonlinear absorption properties can be divided into three characteristic regions, namely P(12)–P(16), P(18)–P(22), and P(24)–P(30), each of which has distinctive features in the measured transmission as a function of incident radiation intensity. In each region, this transmission behaviour, together with associated dynamical effects such as pulse shaping, are amenable to interpretation by means of a four-level model for the SF6 absorption. The relevant molecular parameters are determined by comparison of theory with experiment.
Parametric excitation of low-frequency convective cell modes by a large amplitude lower-hybrid wave in a plasma
Authors: Shukla P. K. , Yu M. Y.
Published: April 2011

It is shown that convective cell modes can become purely growing modes in the presence of an intense pump wave near the lower-hybrid frequency. The temporal growth rate and threshold of the parametric instability are presented.
Exact transform solution of the one-dimensional special Rayleigh problem
Authors: Barker J. Andrew , Hoare M. R. , Raval S. , Rahman Mizan
Published: April 2011

We examine the full-range initial-value problem for velocity relaxation in a one-dimensional ensemble of Rayleigh test-particles in an arbitrary heat-bath at unit mass-ratio (the special Rayleigh problem). A Laplace transformation method is used to obtain an explicit solution in two independent parity components. Of these, the even component, giving the speed relaxation is obtained exactly and agrees with our previous result obtained by the singular eigenfunction method; the odd component, explicit to within a Laplace inverse provides the time-dependent flux of particles with given velocity. By numerical inversion of the latter, we obtain both time-dependent velocity distributions and the velocity autocorrelation function for equilibrium fluctuations. In keeping with the singular character of the transport equation, the velocity ACF proves to be appreciably non-exponential in character, behaving asymptotically as t−5/2e−t independently of the heat-bath distribution. The complex admittance of a system of charged Rayleigh test-particles is also derived and shown to lead to expected behaviour for dissipation to the heat-bath and phase-lag of response to the applied field.
Comment on the photoionization cross section of lithium and its isoelectronic sequence
Authors: Tiwari P. , Hashim M. A. , Ojha S. P. , Rustgi O. P.
Published: April 2011

The effect of core polarizability on the photoionization cross section of lithium and its isoelectronic sequence is studied. The results are compared with the calculations reported earlier by Tiwari, Hashim, and Ojha as well as with the experimental results.
A tensor notation for many-body diagrams
Authors: Wise M. B. , Trainor L. E. H.
Published: April 2011

A tensor notation is introduced which is particularly convenient for the systematization and enumeration of topologically distinct many-body diagrams.
Confinement of a fusion plasma by a cold gas blanket
Authors: Ahlborn Boye
Published: April 2011

The particle end losses from a linear magnetic fusion reactor can be suppressed by establishing an ablation front in a cold gas blanket. The power density W(W/cm2) to drive the thermal front may be drawn from inside (energy end losses) or outside (auxiliary heating). With W below 109 W/cm2 and a D–T blanket the particle outflow is retarded. With higher W values the flow is completely stopped and the fusion plasma is recompressed by a shock wave traveling inwards from the ends.
Positron annihilation in alloys
Authors: Hong K. M. , Carbotte J. P.
Published: April 2011

A coherent potential approximation (CPA) treatment of positron annihilation in an alloy is presented. Simple formulae for the spatial and the momentum distributions of the positrons are derived. Numerical computations are performed to illustrate the effects of the smearing of the positron momentum distribution and of the electron Fermi momentum of the annihilation photon momentum distribution.
Application of the two state approximation to positronium formation in hydrogen
Authors: Kulhar V. S. , Shastry C. S.
Published: April 2011

A generalized form of Band's theory for rearrangement collisions based on the two state approximation in time dependent quantum-mechanical formalism is used to investigate the positron hydrogen charge exchange problem. The formalism takes into account the nonorthogonality of the rearrangement channel. The effect of nonorthogonality is to raise the cross sections from first Born results. At high energies our results approach Born results. Comparison with other calculations is also reported in the energy region 1.5 to 10 Ry.
Interactions dans une chaîne de sphères ou de cavités alignées. Plasmons de surface et énergie de Van der Waals
Authors: Ronveaux A. , Moussiaux A. , Lucas A. A.
Published: April 2011

The eigenmodes of surface plasmon oscillation for an arbitrary number of aligned spheres or spherical cavities are given by a power series of the radius–distance ratio. The Van der Waals energy is calculated in first approximation for an arbitrary chain, and in second approximation for an array of two holes and two spheres.The error due to the neglect of all interactions except that between nearest neighbors is analysed in detail together with the bands of the infinite chain in the nearest neighbor approximation. [Journal translation]
Surface plasmon oscillations for different geometrical shapes
Authors: Moussiaux A. , Ronveaux A. , Lucas A.
Published: April 2011

The eigenmode of surface plasmon are obtained for different geometries. The results are valid for voids and for particles and give the eigensurface mode of spheroids, paraboloids, cones, and multi-edges. Limiting cases, obtained by asymptotic development, or particular cases useful in some physical situations are studied in more detail: spheroïdal or paraboloidal needles or craks, spheroidal or paraboloidal disks, whisker diode geometry, and blades perpendicular to a plane.
The fluorescence spectrum of NO2: rotationally-forbidden bands and their interpretation
Authors: Bist H. D. , Brand J. C. D. , Hoy A. R.
Published: April 2011

Fluorescence of NO2 excited near 5000 Å at low gas pressure is predominantly 'parallel' in type, i.e., the values of the quantum number K in the initial state of the excitation, the intermediate (excited) state, and the final state(s)of the emission are all equal, Ki = K′ = Kf. However, a considerable number of the weaker fluorescence bands do not conform to this pattern; instead, they correspond to even-parity differences between the initial and final value of K, |Kf − Ki| = 2, 4, or 6, indicating that K (though not N) is a poor quantum number in the upper electronic state of the excitation–emission sequence. The observations are analyzed in terms of a mechanism in which the vibronic coupling between the 2B2 excited state and high vibrational levels of the ground state creates conditions where the asymmetry of the 2B2 basis state produces unexpectedly large couplings between hybrid states of the same parity in K.
Effect of the exchange charge polarization on the photoelastic behaviour of diatomic crystals
Authors: Sharma J. C. , Sharma H. P. , Shanker Jai
Published: April 2011

An analysis of the photoelastic behaviour of diatomic crystals is presented on the basis of the shell model including the effect of exchange charge polarizations. The strain derivatives of the electronic polarizabilities and dielectric constants calculated for alkali halides, MgO, ZnS, and CdS crystals compare well with the available experimental data.
The phonon spectrum of crystalline tellurophene-d0 and tellurophene-d4
Authors: Cataliotti Rosario , Paliani Giulio
Published: April 2011

The phonon spectra of tellurophene-d0 and tellurophene-d4 at 75 K have been studied and the exciton splittings of the fundamental modes have been assigned. The spectra are in accord with centrosymmetric factor group predictions, assuming a Cs site symmetry and a [Formula: see text] space group. In the circumstances, crystals of tellurophene have four molecular units per unit cell and become isomorphous with other aromatic heterocyclic crystals. Two-phonon processes, revealed for thick samples, are associated with internal + internal and internal + external combinations. Some of these last are accounted for by K ≠ 0 critical points selection rules.
Les fluctuations dans le calcul des inerties collectives
Authors: Amiot Pierre
Published: April 2011

A new canonical approach is proposed to obtain an auxiliary Hamiltonian, replacing Lipkin's, used in the derivation of the variable coefficient formula (VCF) for calculating collective inertiae in variational frameworks such as Hartree–Fock in nuclear physics. The method solves the center of mass exactly without any contributions from the fluctuations of the intrinsic state as opposed to the VCF which cannot guarantee this property.
Single electron capture by Ar2+ in Ne, Ar, and Kr gases
Authors: Suk H. C. , Guilbaud A. , Hird B.
Published: April 2011

Measurements of single electron capture cross sections by Ar2+ ions in thin targets of neon, argon, and krypton have been made with an absolute accuracy of about 5%. The detection system was constructed so as to have a uniform efficiency over the range of angles and energies at which the singly charged Ar+ ions were produced in the charge exchange. Discrepancies with the extrapolated absolute values of previous measurements were found, but the energy variations of the cross section are in much better agreement. It seems possible to account for the energy variation of the cross sections with the two state theory when it is assumed that the ions of both the initial and the final states are all in their ground states.
A study of levels in 147Nd using the (d,t) reaction
Authors: Straume O. , Burke D. G.
Published: April 2011

The 148Nd(d,t)147Nd reaction has been studied using 12 MeV deuterons. The reaction products were analyzed with an Enge-type magnetic spectrograph and detected with photographic emulsions, giving peak widths (FWHM) of approximately 8 keV. The present results confirm previous indications that the highest energy proton group found in an early 146Nd(d,p) investigation does not correspond to the ground state transition, but to the level at an excitation energy of 50 keV. The (d,t) angular distributions were used to determine l-values for a number of transitions. A striking similarity is noted with the energy levels and spectroscopic strengths previously found in the isotones 149Sm and 151Gd. With the exception of the h11/2 state, it is possible to explain the observed strengths in terms of the spherical shell model, although there is fragmentation of the spherical states.
Elementary excitations in normal liquid 3He
Authors: Glyde H. R. , Khanna F. C.
Published: April 2011

The density and spin-density excitations in normal liquid 3He observed in recent neutron scattering experiments, are described here using a simple RPA model employing the Landau quasiparticle–quasihole interaction. The purpose is to test how well a simple extension of the Landau theory, known to describe excitations of vanishing wave vector Q and frequency ω, can describe the full dynamic form factor, S(Q,ω), at all Q and ω. The extension is made by replacing the Landau dynamic susceptibility, χ(Q,ω), by the RPA expression. For Q ≥ 10 nm−1 the spin-symmetric Landau interaction is also reduced to allow for multi-quasiparticle–quasihole contributions to the density excitations.At low temperature, T ≤ 50 mK, the model predicts a well defined 'zero-sound' mode in the density excitations and a 'paramagnon' peak at low frequency in the spin-density excitations. The good agreement of the calculated S(Q,ω) with that observed by Sköld, Pelizzari, Kleb, and Ostrowski at T = 15 mK for Q ≤ 15 nm−1 suggests that the extension works surprisingly well. The temperature dependence of S(Q,ω) is also investigated by allowing χ0(Q,ω) to vary with T and by including the temperature dependence of the Landau interaction, indicated by thermodynamic properties. This leads to a loss of structure in S(Q,ω) at higher temperature in agreement with the observations of Stirling, Scherm, Hilton, and Cowley at T = 0.63 K.
Scattering of electromagnetic waves by a charged sphere
Authors: Bohren Craig F. , Hunt Arlon J.
Published: April 2011

The problem of scattering of electromagnetic waves of arbitrary frequency by a homogeneous, isotropic sphere which carries excess surface charges can be solved under the assumption that there exists a linear relation between surface current density and electric field. The scattering coefficients so obtained are formally different from those in the standard Mie–Debye theory. Whether or not there is any observable difference between scattering by a charged and otherwise identical uncharged sphere depends upon the value of a phenomenological surface conductivity or, equivalently, surface dielectric function. For sufficiently small particles the effect of surface charges is merely additive, the effective dielectric function is the sum of bulk and surface dielectric functions.
4d85p → 4d85s transitions in Sn VI
Authors: Srivastava R. P. , Joshi Y. N. , Kleef TH. A. M. van
Published: April 2011

The spectrum of tin has been observed on a 6.650 m normal incidence spectrograph at the Zeeman Laboratory in Amsterdam in the region 700–1300 Å. The source used was a sliding spark operated under different experimental conditions. The transitions 4d85p → 4d85s in Sn VI have been identified and all levels belonging to the 4d85s and 4d85p configurations have been established. The level values of the levels 4d8(3F)5p4F7/20 and 4d8(3P)5p4D1/20 reported earlier have been revised from 326 654.3 to 326 591.7 cm−1 and from 335 288.4 to 335 353.0 cm−1, respectively. The parametric level fitting calculations are in good agreement with the present analysis. Two hundred and forty-six additional lines in this spectrum have been classified. Revised energy level values for Sn V spectrum have also been calculated.
Temperature dependence of the electrical resistivity of copper at low temperatures
Authors: Moussouros P. K. , Kos J. F.
Published: April 2011

Precise measurements of the electrical resistivity of pure copper samples have disclosed two discontinuities in the temperature dependence of the resistivity. They occur at approximately 6.7 K and near 12.1 K. The second is associated with impurity effects whereas the first appears to be a characteristic of the metal itself. It is similar to the discontinuity previously observed in the temperature dependence of the electrical resistivity of Ag by Kos and independently by Ehrlich and Schriempf and attributed by the former to one-step umklapp processes.
Measurements of the total reaction cross section for protons on Ti and B between 20 and 50 MeV
Authors: Nasr T. N. , Sourkes A. M. , Margaziotis D. J. , Carlson R. F. , Cox A. J.
Published: April 2011

Using a variation of a standard attenuation technique, total proton reaction cross sections (σR) have been measured for Ti and B at eight incident proton energies between 20 and 50 MeV at the University of Manitoba Cyclotron Laboratory. The Ti cross sections are presented along with existing reaction cross section data and are compared with optical model predictions for σR. The B cross sections are compared with σR for the nearby elements Be and C. The B and Ti results are also compared to predictions of the opaque-nucleus model.
The Fröhlich Hamiltonian: mathematical results. II. Hamiltonian without cut-off
Authors: Dormale Bernard M. de , Bader Georges
Published: April 2011

We study the Fröhlich Hamiltonian without cut-off: we prove its self-adjointness, derive some of its properties, and give its relationship with the Hamiltonian with cut-off.
Nonlinear photodissociation of molecular iodine
Authors: Tai C. , Dalby F. W.
Published: April 2011

Strong ultraviolet fluorescence originating from the radiative decay of the atomic iodine levels (3P2)6s[2]3/2 at 56092.88 cm−1 and (3P2)6s[2]5/2 at 54 633.46 cm−1 was observed when a pulsed laser beam was focused in a cell containing iodine vapour. The fluorescence intensity varied quasi-continously when the laser wavelength was scanned from 3950 to 4500 Å. Over 40 resonances at the frequency of one-photon transitions originating from the same two atomic iodine levels were observed in the fluorescence spectrum as well as in the photoionization spectrum. The intensity of both the fluorescence and the photoionization was found to vary quadratically with the laser power. The excited iodine atoms are formed by a coherent two-photon transition in molecular iodine followed by saturated photodissociation.
Cosmic antiproton–proton flux ratio at the top of the atmosphere
Authors: Bhattacharyya D. P. , Sarkar Kalpana , Basu D. , Roychoudhury R. K.
Published: April 2011

The cosmic antiproton–proton flux ratio at the top of the atmosphere has been calculated using a Bose type distribution of the differential cross section for [Formula: see text] inclusive reactions of the form [Formula: see text] at ISR energies and the estimated flux ratio is found to be 9.17 × 10−4, which is in accord with the values presented by Hayakawa and Rosen.
Macroscopic theory of dielectric solids. II. The theory of Brillouin scattering from rare gas crystals
Authors: Sipe J. E.
Published: April 2011

We extend the macroscopic theory of dielectric solids to include the description of the Brillouin scattering of light by deriving expressions for the dielectric constant in the absence of strains, and for the Pockels elasto-optic coefficients, from a microscopic model appropriate for the rare gas crystals. The constituent atoms are regarded as polarizable particles coupled by the dipole–dipole interaction, which we treat by introducing the usual microscopic effective electric field, and by the short-range higher multipole and Vander Waals interactions, which are included in the microscopic model by associating with each atom an effective polarizability that depends on the distance between the atom and its nearest neighbors. We define the macroscopic fields by space averaging over volume elements of linear dimensions Δ satisfying a [Formula: see text], where a is the interatomic spacing and λ the wavelength in vacuo; using a new theorem relating the microscopic effective electric field and macroscopic electric and polarization fields, we are able to derive a constitutive relation, involving the strain tensor, from our microscopic model. While the largest contribution to the Pockels coefficients appearing in this relation is due to variations in the dielectric tensor that result from deviations of the macroscopic density from its value in the absence of strains, we find that two other contributions appear because strain fields affect the dielectric tensor by changing both the local field and the values of the effective polarizabilities. If the short-range interactions are neglected, our theory leads to the same ratios of Pockels coefficients obtained from the microscopic scattering theory of Werthamer (when an error in that theory is corrected), but the values of the Pockels coefficients we obtain contain a local field correction, which the microscopic scattering theory does not take into account. The contribution of the short-range interactions to the Pockels coefficients is estimated by obtaining values of the effective polarizabilities from calculations of the polarizabilities of pairs of rare-gas atoms; we find that the contribution is non-negligible and thus demonstrate that new information on these short-range interactions can be obtained from the results of Brillouin scattering experiments.
On the theory of the nonlinear effect in polar liquids
Authors: Grosse Constantino , Brito Pedro
Published: April 2011

It is shown that in order to relate the permittivity ε = ε0[1–λE2] of a nonlinear dielectric with molecular parameters using Onsager's formalism, the condition to be used is that the average value of the dipolar potential outside the cavity and with an applied field must vanish. Consequently, the potential for a rigid dipole in a spherical cavity filled up with a continuum ε∞ and surrounded by a nonlinear dielectric immersed in a strong applied field are calculated both inside and outside. The average value of the external dipole moment is deduced from the torque exerted by the field outside the cavity on the sources of the applied field.The expression thus obtained for the parameter λ leads to values that are always positive and slightly smaller than those corresponding to earlier studies. The expression deduced for the permittivity in weak fields ε0 introduces a correction to Onsager's equation consisting of a factor multiplying the square of the molecular moment. In contradiction with recent results by other authors, this factor is always less than 1 and its value is of the order of 0.9.
Hamilton's principal function for the Brownian motion of a particle and the Schrödinger–Langevin equation
Authors: Razavy M.
Published: April 2011

The Brownian motion of a particle coupled to a heat bath can be derived from an exactly solvable many-body system. This motion is governed by the Langevin equation in Newtonian mechanics, and by an operator equation formally identical to the Langevin equation when the system composed of the particle plus the heat bath is quantized. To get this formal similarity between the classical and the quantal equations of motion of the particle, the classical dissipative system is formulated in terms of a modified Hamilton–Jacobi equation and is then quantized using the Schrödinger method. The result is identical with the Schrödinger–Langevin equation that has been obtained by quantizing the entire system and then isolating the motion of the particle. The non-linear wave equation describing the motion of a particle subject to conservative and time-dependent forces as well as frictional forces has been applied to the problems of motion of a wave-packet, and of the scattering and trapping of heavy-ions.
Une nouvelle équation intégrale pour l'étude de la radiation scalaire dans une cavité
Authors: Darling Byron T. , Imbeau Jacques A.
Published: April 2011

We derive an integral equation of the first kind connecting the surface values and the normal derivative for a regular solution inside a closed cavity of the Helmholtz equation. This integral equation has two advantages over the usual limit form of integral equations where the field point must lie on the boundary and the kernel is singular, namely, the field point may be anywhere inside or outside the cavity, and the kernel is regular. Analytic solution of our integral equation is obtained for the special cases of monopole and of dipole sources at the center of a sphere (Dirichlet's condition). The next paper will apply this integral equation to prolate spheroidal cavities.
The spin model. II. Analysis of high temperature series expansions of some thermodynamic quantities in three dimensions
Authors: Rogiers J. , Betts D. D. , Lookman T.
Published: April 2011

In this paper we reanalyze the series for the fluctuation of the order parameter, the fourth order fluctuation in the order parameter, and the specific heat for the spin [Formula: see text] model on three dimensional lattices. We find for the exponents, respectively, γ = 1.333 ± 0.001, γ2 = 4.725 ± 0.01, and α = 0.00 ± 0.04. We find no evidence for a correction to scaling term with exponent [Formula: see text] for the specific heat or for the susceptibility. Precise estimates for critical entropy and critical energy are obtained. From the critical amplitudes we obtain further support for the lattice–lattice scaling hypothesis and the one scale factor universality hypothesis.
The gravitational field about a classical spin- particle
Authors: McKeon Gerry
Published: April 2011

Recently Grassmann variables (anticommuting c-numbers) have been introduced into classical physics in order to describe spin. These results can be used to examine the classical gravitational field about a spin- [Formula: see text] particle.
Crystal equilibrium and lattice dynamics of face-centered cubic metals
Authors: Gupta O. P. , Kharoo H. L. , Hemkar M. P.
Published: April 2011

A lattice dynamical model that assumes short range pairwise forces effective up to second nearest neighbours and electron–ion interaction on the lines of Bhatia is considered to study the crystal dynamics of fcc metals. The authors consider an appropriate value of the screening parameter and the band structure effects have been introduced in a satisfactory manner in the present calculations. The volume force is averaged over the whole Wigner–Seitz sphere. The ionic lattice is in equilibrium in a medium of electrons. The present theory has been satisfactorily applied to compute dispersion curves, Debye characteristic temperatures, and temperature dependence on the Debye–Waller factors of thorium.
The characterization of pure and niobium-doped crystals of strontium titanate using Hall, electrical conductivity, and optical absorption data
Authors: Perluzzo G. , Destry J.
Published: April 2011

A description is given of the heat treatment, under controlled conditions, of crystals of strontium titanate, both pure and niobium-doped, and of the effect of this treatment on the defect states in this material. Our analysis is based on evaluation of the results of electrical conductivity and Hall effect measurements, and those of optical absorption.
Beam-foil spectroscopy of oxygen in the wavelength region from 270 to 490 Å
Authors: Pinnington Eric H. , Donnelly Keith E. , Kernahan J. Anthony , Irwin David J. G.
Published: April 2011

We have used the beam-foil technique to study the spectrum of oxygen between 270 and 490 Å. We have measured the mean lives of the 3d2F, 3d4P, 3d4D, 3d′ 2D, 3d′ 2F, 4d4P, and 4d4D terms of O II, the 3s1P0, 3s3P0, 3S5P, 3s′ 3D, 3d3P, 3d3D, 3d3F, and 3d5P terms of O III, and the 3S2S, 3P2P0, and 3s4P0 terms of O IV. All cascade components are adequately explained. Good agreement is found with previous measurements in most cases, but significant discrepancies are found with some earlier results obtained using branches above 2000 Å. Generally satisfactory agreement is also found with theoretical predictions, although disagreement is found for several members of the 2p3–2p23d array in O II f-Values are computed for 18 individual lines, and compared with other experimental and theoretical results. Finally, we discuss briefly the f-value trends along the 2p23P–2p3s3P0 (O III), 2p21D–2p3s1P0 (O III), 2s2p24P–2s2p(3P0)3s4P0 (O IV), and 2p2P0–3s2S (O IV) isoelectronic sequences.
Mean-life measurements for some fluorine transitions in the quartz region
Authors: Pinnington E. H. , Irwin D. J. G. , Livingston A. E. , Kernahan J. A. , Gosselin R. N. , Berry H. G.
Published: April 2011

The beam-foil technique has been applied to the measurement of the mean lives of seven terms in F III and three terms in F IV, giving rise to transitions in the wavelength range 2150 to 3200 Å. The results are compared with other experimental and theoretical values. Forecasts are made for f-values of some F IV transitions below 500 Å in the 2s2p3–2s22p3p array. Examples of the application of the arbitrarily normalized decay curve (ANDC) method for including the effects of cascade repopulation in the data analysis are discussed.
Optical absorption by impurities in semiconductors
Authors: Barrie Robert , Chow H. -C.
Published: April 2011

Parts of the linear and quadratic coupling of the electron–phonon system are included in a discussion of optical absorption and emission by an electron that is bound to an impurity in a semiconductor and is in interaction with the lattice vibrations. An adiabatic approach is not used. Comparison is made between an approach based on the Bethe–Sommerfeld expression in the representation in which the Hamiltonian is diagonal and one based on a correlation function approach.
Perturbation theory of the pair correlation function in molecular fluids
Authors: Henderson R. L. , Gray C. G.
Published: April 2011

We study the perturbation theory of the angular pair correlation function g(rω1ω2)in a molecular fluid. We consider an anisotropic pair potential of the form u = u0 + ua, where u0 is an isotropic 'reference' potential, and for simplicity in this paper we assume the perturbation potential ua to be 'multipole-like', i.e., to contain no l = 0 spherical harmonics. We expand g in powers of ua about g0, the radial distribution function appropriate to u0. This series is examined by expanding ha = h−h0 (where h = g−1) and its corresponding direct correlation function ca in spherical harmonic components. We consider approximate summations of the series in ua that automatically truncate the corresponding harmonic series, so that the Ornstein–Zernike (OZ) equation relating ha and ca can be solved in closed form. We first expand ca = c1 + c2 + … where cn includes all terms in ca of order (ua)n. Taking ua to be a quadrupole–quadrupole interaction, we find that a 'mean field' (MF) approximation ca = c1 gives rise to only three nonvanishing harmonic components in ha, so that OZ is solved explicitly in Fourier space. The MF solution for multipoles of general order is given in an appendix. Graphical methods are then used to identify the class of all terms in the ua series that are restricted to the harmonic space defined by MF. A portion of this class can be summed by solving OZ with the closure ca = −βg0ua + h0(ha−ca), where β = (kT)−1, h0 = g0−1 This system is designated as generalized MF (GMF), and solved by numerical iteration. Numerical results from MF and GMF are presented for quadrupolar ua, taking u0 to be a Lennard-Jones potential. Symmetries imposed by the restricted harmonic space are foreign to the full g, yet harmonics within this space are sufficient for evaluation of many macroscopic properties. The results are therefore evaluated in harmonic form by comparison with the corresponding harmonic components of the 'correct' g as evaluated by Monte Carlo simulation.
Electron paramagnetic resonance of Mn2+ doped in alkali trihydrogen selenite single crystals
Authors: Jain Vimal Kumar , Venkateswarlu Putcha
Published: April 2011

The electron paramagnetic resonance spectra of Mn2+doped in MeH3(SeO3)2(Me = Li, Na, K, and Rb) single crystals have been studied at 298 K. In LiH3(SeO3)2, an axis of non-coincidence effect has been observed and Mn2+ spectra show line broadening of outer transitions. In NaH3(SeO3)2, Mn2+ substitutes for Na+ ions and is associated with second nearest neighbour Na+ ion vacancies. Below the ferroelectric phase transition temperature of this crystal every line of the spectrum appears to split into two. The spectra of Mn2+ doped LiH3(SeO3)2 and NaH3(SeO3)2 (in paraelectric phase) have been analysed using the spin-Hamiltonian for rhombic symmetry. However, in KH3(SeO3)2 and RbH3(SeO3)2 the Mn2+ ions give only one line. The linewidths and g values of the lines for KH3(SeO3)2 and RbH3(SeO3)2 are ΔHpp = 154 ± 15 G, g = 1.988 ± 0.008, and ΔHpp = 102 ± 10 G, g = 1.998 ± 0.006, respectively.
The temperature dependence of the 8920 Å band of NO2 and the location of the 000–000 band of the transition
Authors: Merer A. J. , Hallin K-E. J.
Published: April 2011

The absorption spectrum of NO2 cooled to −30 °C has been photographed at high dispersion in the wavelength region 8200–9100 Å. Comparison with the room temperature spectrum shows that weak absorption from the ground state of the molecule underlies slightly stronger 'hot' band absorption at 8920 Å. Franck–Condon calculations based on the relative intensities of absorption bands from the 000 and 010 vibrational levels of the molecule indicate that the 000–000 band of the [Formula: see text] electronic transition lies near 10250 Å (1.21 eV) with a possible uncertainty of one quantum of ν2′ (0.09 eV). This result is in good agreement with the multiconfiguration SCF calculations of Gillispie and Khan (which are at variance with previous experimental deductions on the location of the 000–000 band).Some new assignments have been made in the rotational structure of the 8360 Å band.
Etude expérimentale du décalage de la raie d'inversion J = 13, K = 13 de l'ammoniac 14NH3 en fonction de la pression du gaz
Authors: Mathelin J. P. , Suzeau P. , Lamalle B. , Chanussot J.
Published: April 2011

By using an open cavity Perot–Fabry type video spectrometer, the variation of line width and line shift of J = 13, K = 13 inversion line of ammonia is studied vs. the pressure p of the gas. The following results are obtained: line width parameter Δv/p = 25 ± 1 MHz/Torr, line shift parameter δv/p = 1.9 ± 0.4 MHz/Torr, collisional diameter be = 13.3 Å.
Bound state for a screened impurity in a magnetic field
Authors: Jog S. D.
Published: April 2011

A variational calculation of the ground state energy of an electron bound to a screened impurity in a semiconductor in a magnetic field is presented. The trial wave function is taken to be a product of a Landau wave function and a spherical wave function. We consider and compare the two cases in which the spherical part is chosen to be (i) a Coulomb wave function (after Rau, Mueller, and Spruch) and (ii) a Hulthén wave function.
Decay of 104, 106g, mIn
Authors: Huang H. , Pathak B. P. , Lee J. K. P.
Published: April 2011

The decays of 104,106In produced by (p, xn) reactions have been studied through γ, γ–γ, β, and β–γ spectroscopic methods. The measured β-decay half-lives are 1.8 ± 0.2 min for 104In (5+), 6.2 ± 0.1 min for 106gIn (6+, 7+), and 5.2 ± 0.1 min for 106mIn (3+). The decay schemes of 106m,gIn, 104In are presented.
Lineshape analysis of collision induced spectra of gases
Authors: Hunt J. L. , Poll J. D.
Published: April 2011

A procedure is presented for the analysis of collision induced lineshapes in terms of a two parameter model. The actual lineshape-function used involves a modified Bessel function of the second kind and is particularly suitable for the analysis of lines due to the overlap induction mechanism. The corresponding dipole is represented by two parameters as well, and it is shown that there is a one-to-one relationship between the empirical width parameter and the dipole range. Similarly the strength of the dipole can be related directly to the empirical intensity parameter.The procedure allows a very efficient way of analyzing induced spectra and is applied to a large number of spectra that have been reported in the literature.
High resolution rotation–vibration Raman spectra of benzene. I. The totally symmetric bands of C6H6
Authors: Hollinger A. B. , Welsh H. L.
Published: April 2011

The Raman spectrum of benzene vapour was excited in a multiple reflection Raman cell by an Ar+ laser and was photographed with a spectral slit width of ~0.17 cm−1. All seven Raman-active fundamentals were observed. Analyses of the totally symmetric ν1 and ν2 bands are given in this article. About 150 maxima were observed for ν2 (C—C stretching) and ~100 for ν1 (C—H stretching); the latter was to some extent obscured by the ν15 band. These partially resolved rotational structures were analyzed by setting up suitable schemes of approximate assignments for the maxima and calculating the band constants by a linear least-squares minimization.
Improved treatment of pairing correlation for fast rotating nuclei
Authors: Ghosh M. K. , Majumdar S. R.
Published: April 2011

An improved treatment of pairing correlation at high spin for the rotating nuclei is given by extending the Lipkin–Nogami method. A procedure is outlined to suppress the fluctuation effect due to non-conservation of nucleon number. The gap parameter Δ, the Lagrange multiplier λ, and constant λ2 are determined self-consistently. Numerical computations are performed for [Formula: see text].