bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibrational dependence of the torsional tunneling splitting and the a to b intensity evolution in the OH overtone spectra of CH3OH
Authors: Temsamani M Abbouti , Xu L -H , Perry D S
Published: April 2011

An ab initio investigation of the OH-stretching overtone of methanol is presented aimed at interpretation of two of the interesting features reported in recent supersonic-jet infrared-laser-assisted photofragment spectroscopy (IRLAPS) studies, namely, (i) a monotonic decrease of the torsional E  A splitting as υOH increases, (ii) an evolution of the a-type transition moment towards dominance at higher excitations of the OH-stretching vibration. At the MP2 level with a 6-311+G(3df,2p) basis set, one-dimensional functions for the potential energy, dipole moment (a and b directions), barrier height V3, and torsional constant F have been mapped out as a function of the OH-bond length with the remaining structure relaxed. All ab initio quantities have been expressed as Taylor-series expansions in the dimensionless OH normal coordinate, q. Calculations have been carried out in the harmonic basis set to yield vibrational energies and eigenfunctions. The latter have been used to evaluate the torsional parameters (V3, F) and the resulting E  A torsional splittings at each OH excitation, and to compute the evolution of the infrared transition intensity ratio [Formula: see text]a/b. The ab initio results reproduce the reported decrease in E  A splitting by a factor of 5 in going from υOH = 0 to υOH = 6, with a maximum deviation of 19% at the highest excitation. The calculated variation in [Formula: see text]a/b is in qualitative agreement with the experimental trend, showing the observed sharp rise at high υOH. PACS Nos.: 33.20E, 33.80B
Role of democratic SU2 x n dual-group carrier space and group structure in the superboson quantum-Liouville physics of identical spin ensembles: Maximal n tensor product reduction, via symbolic algebraic combinatorics
Authors: Temme F P
Published: April 2011

Structural aspects of superboson mappings and their dual group-based carrier spaces inherent in quantum-Liouville NMR formalisms are presented for their conceptual role in understanding the transformational properties and the spin dynamics of identical [A]n([Formula: see text]n) spin ensembles or [AX]n systems, given in terms of {Tkq (υ)} º  {|kqυ > >} tensorial bases. Interest in the explicit democratic labelling of the Liouvillian carrier subspaces of [A]n spin ensembles, prompts an examination of the inner products (ITPs) that define the projective carrier space associated with superbosons. A weak-branching (WB) limit (for (bipartite) partitions λ [Formula: see text] n, for n-indexed (SU2 ×)[Formula: see text]n) ITPs gives rise to: (i) maximal coefficient sets for [µ] [Formula: see text] [µ']([Formula: see text]n) irrep products (in Butler's notation), under a sufficiently high (n [Formula: see text] 4µ, 4µ') indexed [Formula: see text]n group, or (ii) to identical numerical {c[Formula: see text], λ' } sequence-ordered sets of reduction coefficients over similar, displaced-sequence fields  on augmenting ITP to [µ] [Formula: see text] [µ''], where µ'' > µ' > µ,  or else (iii) to some (sequence-displaced) subset of the latter. The origins of the decompositional WB limit as part of group structure may be traced to an algorithmic similarity between the LittlewoodRichardson and Young(III) combinatorial rules. Alternative approaches to the bipartite product decompositional mappings are possible, using both (subspatial-restricted) Schur-function techniques of Wybourne and [Formula: see text]16[Formula: see text]n[Formula: see text]28 symbolic algorithmic enumerations based on the SYMMETRICA discrete-maths. package of Kerber et al. (J. Symbolic Comput. 14, 195 (1993)). The nature of maximal sets and scaling in ITP decompositions is established and recognition given to the role of combinatorics, [Formula: see text]n algorithms and the superboson algebras of the SU(2) × [Formula: see text]n group in (multiple) quantized spin physics.

PACS Nos.: 02.10, 03.65Ca, 33.20Vq, 33.25+k
Nouvelle approche de modélisation des transistors micro-ondes MESFET et HEMT
Authors: Touhami R , Yagoub M CE , Baudrand H
Published: April 2011

The authors present an analytical model of current drainsource based on the one established by Chalmers. As the precision of parameters is directly bound to the measured maximal value of the transconductance, a precision level of 25 % is obtained. To improve this precision, the combined optimization algorithm with the Chalmers model is elaborated. The results obtained are very satisfactory. For a mathematical function ψ, with three terms in the saturated region, the influence of the temperature represents correctly the drain current for the voltage near a pinch-off voltage.
Wave scattering from rough cylinders
Authors: Hillion P
Published: April 2011

We present a nonconventional integral equation approach to the scattering of harmonic waves by a smooth or rough perfectly conducting circular cylinder and by a cylinder with a surface impedance. As an application, the case of a corrugated cylinder is investigated.

PACS Nos.: 03.50De, 41.20Jb, 41.60Bq
On the calculation of charge-exchange effects in a relativistic model for (γ n) reactions
Authors: Lotz G M , Sherif H S
Published: April 2011

The charge-exchange contribution to photoneutron emission is calculated in a relativistic model. The emission is regarded as a two-step process consisting of a direct electromagnetic knockout of a proton followed by a (p,n) charge-exchange reaction. The latter step is effected by the isovector components of the scalar and vector mean field optical potentials. A novel procedure, in which the pertinent integral is reduced to a simpler integral in combination with a differential equation, is adopted to evaluatethe transition amplitude. We find that the charge-exchange contribution is comparable in magnitude to the direct contribution over a range of photon energies. There is some dependence on the optical and binding potentials used to calculate nucleon wave functions. As expected, the sum of direct and charge-exchange contributions is not sufficient to account for the observed cross sections, confirming the importance of including meson exchange and isobar currents.

PACS Nos.: 25.20Lj, 25.40Kv, 24.10Jv
The perturbative β-function in the Zumino model
Authors: Clarkson R , McKeon D.G.C.
Published: April 2011

We consider the perturbative β-function in a supersymmetric model in four-dimensional Euclidean space formulated by Zumino. It turns out to be equal to the β-function for N = 2 supersymmetric YangMills theory despite differences that exist in the two models.

PACS No.: 12.60Jv
Maximizing the lateral motion of a curling rock
Authors: Shegelski Mark R
Published: April 2011

A simplified version of a previously proposed model captures the salient features of the motion of a slowly rotating curling rock. The model is used to suggest how standard curling rocks may be modified to maximize the net lateral displacement of a slowly rotating curling rock.

PACS No.: 46.00
Positron impact ionization of hydrogen and the noble gases
Authors: Campeanu R I , McEachran R P , Stauffer A D
Published: April 2011

Based on our previous experience with positron ionization, we propose a simple distorted-wave model for this process and apply it to the ionization of atomic and molecular hydrogen as well as the noble gases. The advantage of having a single method that produces reliable results in all cases is discussed.

PACS No.: 34.85+x
Low-lying spin-wave spectrum of the triangular anti-ferromagnet: A finite-size study
Authors: Trumper A E , Capriotti L , Sorella S
Published: April 2011

We developed a finite-size spin-wave calculation on the Heisenberg anti-ferromagnet on the triangular lattice, which, to order 1/s, favors a singlet (for an even number of sites) ground state. Furthermore, we implement the computation of the low-energy excitation spectrum E (S) where S is the total spin. For s=1/2, the good agreement with the exact diagonalization and quantum Monte Carlo results strengthens the validity of the spin-wave expansion to describe the low-energy spin excitations of the Heisenberg model even in the presence of frustration.

PACS No.: 75.10-b
Magnetic properties of pure deuteronium and diamagnetically-doped hydronium iron jarosite
Authors: Pettigrew K G , Visser D , Harrison A , Nicholson D H , Kilcoyne S H , Manuel P , Murani A P
Published: April 2011

D3OFe3(SO4)2(OD)6 is a model example of an S = 5/2 Kagome anti-ferromagnet that exhibits unconventional two-dimensional spin-glass properties. We report quasi-elastic neutron-scattering data on D3OFe3(SO4)2(OD)6 derived from three-directional neutron spin-polarization analysis in combination with time-of-flight analysis (Δ E [Formula: see text] 1 meV). At 1.5 K, within the time window of the experiment, only 45% of the total elastic magnetic moment is frozen  a broad magnetic response in Q is still observed at temperatures in excess of ten times the spin-glass freezing temperature. The dc-magnetization measurements on H3OFe3xAlx(SO4)2(OD)6 show that dilution of the magnetic lattice with Al3+ disrupts the spin-glass state. Mössbauer measurements indicate that the Al replaces the Fe ions on the magnetic sites of the Kagome lattice, giving rise to two distinct iron sites with equal occupation levels but different hyperfine fields.

PACS Nos.: 75.10N, 75.30C, 75.30H, 75.50L
SrCu2(BO3)2  a two-dimensional spin liquid
Authors: Knetter C , Bühler A , Singh R RP , Müller-Hartmann E , Uhrig G S
Published: April 2011

We study an extended ShastrySutherland model for SrCu2(BO3)2 and analyze the low-lying parts of the energy spectrum by means of a perturbative unitary transformation based on flow equations. The derivation of the one-magnon dispersion (elementary triplets) is discussed. Additionally, we give a quantitative description (symmetries and energies) of bound states made from two elementary triplets. Our high-order results allow us to fix the model parameters for SrCu2(BO3)2 precisely: J1 = 6.16(10) meV, x := J2/J1 = 0.603(3), J[Formula: see text] =1.3(2) meV. To our knowledge this is the first quantitative treatment of bound states in a true 2D model.

PACS Nos.: 75.40Gb, 75.30Kz, 75.50Ee, 75.10Jm
Chiral order of spin-1/2 frustrated quantum spin chains
Authors: Hikihara T , Kaburagi M , Kawamura H
Published: April 2011

The ordering of the frustrated S = 1/2 XY spin chain with the competing nearest- and next-nearest-neighbor anti-ferromagnetic couplings, J1 and J2, is studied by using the density-matrix renormalization-group method. It is found that besides the well-known spin-fluid and dimer phases the chain exhibits a gapless "chiral" phase characterized by the spontaneous breaking of parity, in which the long-range order parameter is a chirality, κl =SxlSyl+1  Syl Sxl+1, whereas the spin correlation decays algebraically. The dimer phase is realized for 0.33 [Formula: see text] j = J2/J1 [Formula: see text] 1.26 while the chiral phase is realized for j [Formula: see text] 1.26.

PACS No.: 75.25
Frustrated order by disorder: The pyrochlore anti-ferromagnet with bond disorder
Authors: Bellier-Castella L , Gingras M JP , Holdsworth P CW , Moessner R
Published: April 2011

The classical Heisenberg anti-ferromagnet on the pyrochlore lattice is macroscopically and continuously degenerate and the system remains disordered at all temperatures, even in the presence of weak dilution with nonmagnetic ions. We show that, in contrast, weak-bond disorder lifts the ground-state degeneracy in favour of locally collinear spin configurations. We present a proof that for a single tetrahedron the ground state is perfectly collinear but identify two mechanisms that preclude the establishment of a globally collinear state; one due to frustration and the other due to higher order effects. We thus obtain a rugged energy landscape, which is necessary to account for the glassy phenomena found in real systems such as the pyrochlore Y2Mo2O7 recently reported by Booth et al. (Phys. Rev. B: Condens. Matter Mater. Phys. 62, R755 (2000).) to contain a substantial degree of bond disorder.

PACS Nos.: 75.10.Hk, 75.40.Mg, 75.40.Gb
Geometric frustration in the mixed layer pnictide oxides
Authors: Enjalran M , Scalettar R T , Kauzlarich S M
Published: April 2011

We present results from a Monte Carlo investigation of a simple bilayer model with geometrically frustrated interactions similar to those found in the mixed layer pnictide oxides (Sr2Mn3Pn2O2, Pn = As, Sb). Our model is composed of two inequivalent square lattices with nearest-neighbor intralayer and interlayer interactions. We find a ground state composed of two independent Néel-ordered layers when the interlayer exchange is an order of magnitude weaker than the intralayer exchange, as suggested by experiment. We observe this result independent of the number of layers in our model. We find evidence for local orthogonal order between the layers, but it occurs in regions of parameter space that are not experimentally realized. We conclude that frustration caused by nearest-neighbor interactions in the mixed layer pnictide oxides is not sufficient to explain the long-range orthogonal order that is observed experimentally, and that it is likely that other terms (e.g., local anisotropies) in the Hamiltonian are required to explain the magnetic behavior.

PACS Nos.: 75.10Hk, 75.40Mg, 75.50-y, 75.25+z
Magnetic ordering and fluctuation in Kagome lattice anti-ferromagnets, Fe and Cr jarosites
Authors: Nishiyama M , Morimoto T , Maegawa S , Inami T , Oka Y
Published: April 2011

Jarosite family compounds, KFe3(OH)6(SO4)2 (abbreviated to Fe jarosite) and KCr3(OH)6(SO4)2 (Cr jarosite) are typical examples of Heisenberg anti-ferromagnets on the Kagome lattice and have been investigated by means of magnetization and NMR experiments. The susceptibility of Cr jarosite deviates from the CurieWeiss law due to the short-range spin correlation below about 150 K and shows the magnetic transition at 4.2 K, while Fe jarosite has the transition at 65 K. The measured susceptibility fits well with the calculated one on the high-temperature expansion for the Heisenberg anti-ferromagnet on the Kagome lattice. The values of the exchange interactions of Cr jarosite and Fe jarosite are derived to be JCr = 4.9 K and JFe = 23 K, respectively. The 1H-NMR spectra of Fe jarosite suggest that the ordered spin structure is the q = 0 type 120° configuration with +1 chirality. The transition is considered to be caused by a weak single-ion type anisotropy. The spin-lattice relaxation rate, 1/T1, of Fe jarosite in the ordered phase decreases sharply with decreasing temperature and can be well explained by the two-magnon process of spin wave with the anisotropy.

PACS No.: 75.25+z
Heavy-fermion behavior of itinerant frustrated systems: β-Mn, Y(Sc)Mn2, and LiV2O4
Authors: Lacroix C
Published: April 2011

These three metallic systems do not exhibit any magnetic ordering despite experiments showing the existence of localized moments with large anti-ferromagnetic exchange: we propose that this is a direct consequence of the strong geometric frustration since Y(Sc)Mn2 and LiV2O4 have the pyrochlore structure, while β-Mn has a more complicated frustrated structure. Another similarity between these compounds is their very large specific-heat coefficient γ = C/T (420 mJ mol1 K2 for LiV2O4). Several explanations have been proposed for this "3d heavy-fermion behavior", including a 3d-Kondo effect. However, the similarities between the three compounds indicate that frustration plays a big role. We describe a new model in which we take into account the existence of two types of 3d-electrons (localized and itinerant) and a frustrated anti-ferromagnetic exchange between the localized 3d electrons.

PACS Nos.: 75.10Hk, 75.50Ee, 75.40Cx, 75.40-s
The foam geometry "paradox"
Authors: Grassia P S , Cilliers J J , Neethling S J
Published: April 2011

Plateau's rule states that bubble lamellae in a foam meet at equal angles. Attempts to rationalize this rule via a naive "force along a tangent line" argument employing vertex variables are shown to fail, since they do not properly account for bubble volume constraints. Indeed Plateau's rule appears to make a foam system overdetermined, in the sense that there seem to be more constraints than available variables. The resolution of this paradox is that the angle constraints of Plateau's rule cannot be regarded as all independent. This is explained in detail for the two-bubble system in two dimensions. By exploiting just pressure-curvature relations and geometry, it is shown that the lamella joining the two bubbles is obliged to subtend precisely the angle needed to satisfy Plateau's rule and minimize energy. Speculations are offered for a many bubble foam.

PACS Nos.: 68.10Cr, 68.15+e
Laser-assisted elastic electron scattering from helium
Authors: Wallbank B , Holmes J K
Published: April 2011

We report measurements of the differential cross section for scattering of electrons, from helium, with energies in the range 120 eV through scattering angles of 14°140° in the presence of a high-intensity carbon dioxide laser. These results were obtained with beam geometries for which the KrollWatson approximation, normally applied to these types of measurements, predicts zero cross sections. The cross sections reported are not zero but confirm similar experiments with argon as the scattering centre.

PACS No.: 34.80Qb
Possible gapless chiral phase in a frustrated S = 1 1D anti-ferromagnet, CaV2O4
Authors: Kikuchi H , Chiba M , Kubo T
Published: April 2011

We have measured magnetic susceptibility and 51V NMR of CaV2O4, a model substance for a frustrated S = 1 spin chain with competing first- and second-neighbor anti-ferromagnetic interactions. Both the low-temperature magnetic susceptibility and the NMR Knight shift did not go down to zero as the temperature was lowered, suggesting that a spin gap is not present in CaV2O4. The absence of a spin gap gives us a clear contrast to the case of the nonfrustrated spin chains, which should have the Haldane gap. Recently published theoretical results for S = 1 XY or XXZ spin chain indicate that the gapless chiral phase could appear in a relatively broad region. Experimental results are discussed in terms of these theoretical predictions. A spin-freezing anomaly was observed at 20 K, reflecting the spin-frustrating nature of the system.

PACS Nos.: 75.30, 75.50
Magnetic susceptibility study of the heavy rare-earth stannate pyrochlores
Authors: Bondah-Jagalu V , Bramwell S T
Published: April 2011

The series of magnetic rare-earth pyrochlore stannates R2Sn2O7 (R = rare earth, except Ce and Pm) have been investigated by powder susceptibility measurements down to T = 1.8 K. The results are compared with results for the analogous titanate series, which are well known frustrated magnets. Unlike the titanates, the whole series can be formed in the cubic pyrochlore structure. Possible experimental advantages of studying the stannates are discussed.

PACS Nos.: 75.10Nr, 75.50Ee, 75.50Lk
Variance measurement of mp/me using cold moleculesThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at University of Windsor, Windsor, Ontario, Canada on 21–26 July 2008.
Authors: Kajita Masatoshi
Published: April 2011

The pure vibrational transition frequencies of magnetically trapped cold XH molecules are useful to detect the variance in the proton-to-electron mass ratio β (X: alkali-earth atom). This paper compares the accuracies of the vibrational transition frequencies for different XH molecules.
The E2 admixtures in mixed multipole lines 459.7 and 564.0 nm of Bi IThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at University of Windsor, Windsor, Ontario, Canada on 21–26 July 2008.
Authors: Werbowy S. , Kwela J.
Published: April 2011

Studies of the M1-E2 interference effect in the Zeeman spectra of forbidden lines 459.7 and 564.0 nm of Bi I are reported. By the use of computer modelling techniques, the simulated contours were fitted to the recorded spectra to determine the electric-quadrupole admixture in forbidden lines. The E2 admixtures found are: (3.49 ± 0.35)% and (37.1 ± 1.8)% for 459.7 and 564.0 nm lines, respectively. Our results are compared with recent theories and other experiments.
Towards numerical implementation of the relativistically covariant many-body perturbation theoryThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at University of Windsor, Windsor, Ontario, Canada on 21–26 July 2008.
Authors: Hedendahl Daniel , Lindgren Ingvar , Salomonson Sten
Published: April 2011

The standard procedure for relativistic many-body perturbation theory (RMBPT) is not relativistically covariant, and the effects of retardation, virtual-electron-positron-pair, and radiative effects (self-energy, vacuum polarisation, and vertex correction) — the so-called QED effects — are left out. The energy contribution from the QED effects can be evaluated by the covariant evolution operator method, which has a structure that is similar to that of RMBPT, and it can serve as a merger between QED and RMBPT. The new procedure makes it, in principle, possible for the first time to evaluate QED effects together with correlation to high order. The procedure is now being implemented, and it has been shown that the effect of electron correlation on first-order QED for He-like neon dominates heavily over second-order QED effects.
Critical examination of isotope shift and fine structure measurements for optical transitions in 6,7LiThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at University of Windsor, Windsor, Ontario, Canada on 21–26 July 2008.
Authors: Noble George A. , van Wijngaarden William A.
Published: April 2011

Precise isotope shift and fine structure measurements are critically reviewed. Each experiment was checked for whether the data found for different transitions yielded consistent values for the difference in mean-square nuclear charge radius Δr2 of 6,7Li. Experiments that passed this test found Δr2 = 0.735 ± 0.036, 0.755 ± 0.023, and 0.739 ± 0.013 fm2 by studying the Li+ 1s2s 3S→1s2p 3P transition, the Li D lines and the Li 2S1/2→3S1/2 transition, respectively. These data determine the difference in mean-square nuclear charge radius 25 times more accurately than electron scattering. Similarly, averaging the fine structure data from the same experiments gives 62 678.75 ± 0.55 MHz for the 7Li+ 1s2p 3P1–2 interval, in good agreement with theory. The results for the 6,7Li 2P fine structure intervals, 10 0.52.954 ± 0.049 and 10 053.154 ± 0.040 MHz, exceed computed values by 2 MHz and yield a splitting isotope shift, which is nearly a factor of 2 lower than a theoretical estimate.
THE SUDDEN INCREASE IN COSMIC RAY INTENSITY, NOVEMBER 19, 1949
Authors: Rose D. C.
Published: April 2011

Cosmic ray counter telescopes were in continuous operation on November 19, 1949, at Ottawa (geomagnetic lat. 56.8°N) and at Resolute (geomagnetic lat. 83°N) in the Canadian Arctic. The two sets of apparatus were identical and consisted mainly of two counter telescopes, one with six inches and the other with 14½ inches of lead between counters. At Ottawa the counting rates of the individual counter trays were recorded as well as that of the coincidences.On November 19 at about 1048 GMT a sudden increase occurred at Ottawa. The maximum intensity reached about 70% above normal in a few minutes, then decayed slowly to normal in about four hours. The increase was similar in both counter telescopes and in the individual counter trays. At Resolute an increase was noted but of a different type. The intensity did not rise suddenly but increased slowly to about 20% above normal and returned to normal again in about three hours, centered about 1140 GMT. These results and those of other observers indicate that the beam of rays responsible for this increase must strike the earth on a limited area only. Some deductions can be made about the extent of this area.
THE COLLISION MATRIX FOR THE COMPOUND NUCLEUS
Authors: Newton T. D.
Published: April 2011

The nuclear collision matrix is calculated under the restrictions of the compound nucleus hypothesis. The matrix so found contains only one undetermined function, τ(E), a phase shift caused by nuclear interaction. Cross sections are evaluated in terms of τ(E), a set of constants, and functions determined by the non-nuclear potentials.
ON THE THERMODYNAMICS OF WAVE FIELDS
Authors: Scheidegger A. E. , McKay C. D.
Published: April 2011

It is shown that the thermodynamic functions cannot be defined for a non-quantized field theory in the usual way; i.e., if there exists a partition function in Gibbs' sense at all, [Formula: see text] is certainly not the correct one.
SOME DIRECTIONAL CORRELATION FUNCTIONS FOR SUCCESSIVE NUCLEAR RADIATIONS
Authors: Hess F. G.
Published: April 2011

A method of evaluating the sums of angular momentum coefficients appearing in the directional correlation function for successive nuclear radiations is presented. The sums are evaluated for the simplest cases and alpha–gamma and gamma–gamma correlation functions are calculated for these cases—the angular momentum quantum number of one of the emitted particles being arbitrary and that of the other being 1 or 2.
SPINORS IN THE DYNAMICAL THEORY OF SPINNING PARTICLES
Authors: Shanmugadhasan S.
Published: April 2011

The correspondence between self-dual six-vectors and symmetric spinors of the second rank is used to put into spinor form the rotational equations of motion of a particle analogous to a pure gyroscope or to a symmetrical top. These equations are then split up into an equivalent system of equations in terms of spinors of the first rank. The Lagrangian of each system is set up, and the canonically conjugate variables obtained from it in terms of covariant spinors. But the canonical variables, being not all independent, lead to weak equations in the sense of Dirac. Therefore, Dirac's generalized Hamiltonian dynamics is used in the canonical formulation in terms of Poisson Brackets. The detailed discussion of the symmetrical top case shows that, though the fundamental Poisson Brackets for the total spin angular momentum and the "spin" are the usual ones, those Poisson Brackets-involving the derivative of the "spin" are not unique.
STATISTICS OF THE MEAN DEVIATION METER
Authors: Keeping E. S. , Happ W. W.
Published: April 2011

The mean deviation is evaluated for a number of distributions of a Poisson or similar type, such as arise with counters, scaling circuits, and in particular with the mean deviation meter described by Greenberg and Happ. The mean deviation for some distributions is fairly readily obtainable, but for the charge on a single tank circuit and also for the difference of charges on two tanks with different decay constants it is necessary to obtain the probability density. Exact expressions for these density functions are given, and also approximations from which the mean deviation can be calculated.
AN EXPERIMENTAL STUDY OF BAND INTENSITIES IN THE FIRST POSITIVE SYSTEM OF N2: I. VIBRATIONAL TRANSITION PROBABILITIES
Authors: Turner R. G. , Nicholls R. W.
Published: April 2011

Integrated intensities of 52 bands of the N2 first positive system have been measured using a recording infrared spectrometer. These data have been interpreted as vibrational transition probabilities which were compared with theoretical values calculated under the assumption that the electronic transition moment is independent of internuclear separation. The comparison shows that the assumption is not valid for this electronic transition.
DENSITY EFFECTS IN THE RAMAN SPECTRUM OF AMMONIA
Authors: Plint C. A. , Small R. M. B. , Welsh H. L.
Published: April 2011

The Raman spectra of ammonia as a high pressure gas, liquid, solid, and aqueous solution are compared with the spectrum of the low pressure gas. At gas pressures up to 80 atm. no appreciable hindering of rotation is present; a weak satellite of the ν1 band is an unexplained feature of the spectrum at high pressure. The spectra of the liquid, solid, and aqueous solution are interpreted without postulating dimerization; the three higher frequency maxima can be assigned to the 2ν4, ν1 and ν3 vibrations if it is assumed that hindering of rotation is almost complete. The rotational fine structure found by early workers for the aqueous solution could not be observed even at high dispersion.
A PANORAMIC MASS SPECTROSCOPE FOR KINETIC STUDIES
Authors: Leger Edouard G.
Published: April 2011

A mass spectroscope capable of recording the trend of many chemical species in rapid gas-phase reactions is described. The instrument represents a departure from analytical mass spectrometric practice by using a molecular streaming source, rapid electric scanning, an electron multiplier ion detector amplifier, and a cathode ray tube display. A 40 peak spectrum can be scanned in five milliseconds and recorded by a motion picture camera. A few results obtained with this instrument in the study of diethyl ether cool flames are given.
MEASUREMENTS OF SPECTRAL AND ANGULAR DISTRIBUTIONS OF SECONDARY GAMMA-RAYS IN MATTER
Authors: Whyte G. N.
Published: April 2011

The distribution in energy and angle of the secondary gamma radiation emerging from the face of a concrete barrier containing a point source of cobalt-60 has been measured as a function of barrier thickness. Results on energy spectra and angular distributions are presented, and some of their features are compared with theoretical predictions. The operation of the two-crystal spectrometer and the photographic system for recording pulse-height distributions are described in some detail.
A METHOD FOR THE EVALUATION OF SOME LATTICE SUMS OCCURRING IN CALCULATIONS OF PHYSICAL PROPERTIES OF CRYSTALS. II
Authors: Benson G. C. , Schreiber H. P.
Published: April 2011

The methods of a previous paper are applied to the evaluation of lattice sums of the form[Formula: see text]Useful transformations result when either r or s is even but not in general when both r and s are odd. A table of the function[Formula: see text]for integral values of t from 5 to 30 is presented. This permits the extension of the method to the cases r = 1, s = 1 and r = 1, s = 3.
EDGE ENERGIES OF ALKALI HALIDE CRYSTALS
Authors: Schreiber H. P. , Benson G. C.
Published: April 2011

Theoretical calculations of the energies of <100> edges of sodium and potassium halide crystals are described. The present computations differ from those of previous workers by the inclusion of terms arising from van der Waals forces. It appears that these forces make a significant contribution to the edge energy.
ELECTRICAL BREAKDOWN IN ARGON AT ULTRAHIGH FREQUENCIES
Authors: MacDonald A. D. , Matthews J. H.
Published: April 2011

Measured values of breakdown electric fields in pure argon gas are presented. Measurements were made in two resonant cavities at a frequency of 2800 Mc./sec. and for pressures varying from 4 × 10−2 to 200 mm. of mercury. The present results are in agreement with those of Krasik, Alpert, and McCoubrey.
HIGH RESOLUTION RAMAN SPECTROSCOPY OF GASES: VII. ROTATIONAL SPECTRA OF s-TRIAZINE AND s-TRIAZINE-d3
Authors: Lancaster J. E. , Stoicheff B. P.
Published: April 2011

The pure rotational Raman spectra of s-triazine (C3H3N3) and s-triazine-d3 (C3D3N3) vapor were photographed in the second order of a 21-ft. grating spectrograph. The rotational constants were found to be B0(C3D3N3) = 0.21460 ± 0.00008 cm−1 and B0(C3D3N3) = 0.19358 ± 0.00015 cm−1. These values, together with the assumption that the molecule is planar and has a CH bond length of 1.084 Å, give the following values for the structural parameters: r0(CN) = 1.338 ± 0.001 Å, [Formula: see text]NCN = 127°, and [Formula: see text]CNC = 113°.
LATTICE DISTORTION IN TERMINAL SOLID SOLUTIONS OF THE FIRST LONG PERIOD TRANSITION METALS AND COPPER
Authors: Pearson W. B.
Published: April 2011

Collected data of the gross lattice distortion in solid solutions of the First Long Period elements in each other and in copper are given together with similar data for B group solutes in Cu, Ag, and Au. It is shown that there is no correlation between the size of the lattice distortion and the solid solubility of the First Long Period transition metals in copper.
THE PHOTOPROTONS EMITTED FROM CARBON AND NITROGEN NUCLEI
Authors: Livesey D. L.
Published: April 2011

The photoprotons from carbon have been studied by exposing propane gas to bremsstrahlung of maximum energy 35 Mev. and recording the charged particles produced in photographic plates. The energy distribution displays a peak near 6.0 Mev. which is related to the position of the dipole resonance in C12 nuclei. The angular distribution of protons near the peak energy agrees closely with a function f(θ) = A + Bsin2θ but at higher energies most of the protons are emitted at forward angles. Nitrogen gas has also been bombarded with bremsstrahlung of maximum energies 30 and 70 Mev. The energy distributions of the photoprotons are interpreted in terms of known reactions in the N14 nucleus.
THE VARIATION WITH SIDEREAL TIME OF RADIO STAR SCINTILLATION RATES
Authors: Reid G. C.
Published: April 2011

Long-term analysis of the scintillation rate of the radio star Cassiopeia A at a frequency of 50 Mc./s. has been carried out using data obtained at Ottawa and Saskatoon. It is found that the variation of scintillation rate with sidereal time can be explained by assuming the ionospheric irregularities responsible for the scintillations to be greatly extended along the direction of the earth's magnetic field, and to have a drift motion whose average direction appears to be around an axis passing through the earth's dip-pol
ON POSSIBLE REALIZATIONS OF MACH'S PROGRAM
Authors: Kaempffer F. A.
Published: April 2011

By "Mach's Program" is meant the intention to understand all inertial effects as being caused by gravitational interaction. Within the framework of a simplified theory of gravitation, based upon ideas by Hund and Sciama, it is easy to invent primitive cosmological models for which Mach's Program is realized. In particular, it is possible to understand the inertia of a linearly accelerated body as being due to radiative gravitational interaction with all other masses in the universe. If it is true that anti-matter has negative gravitational mass, as has been suggested by Morrison and Gold, then one may look upon Newton's second law as a manifestation of the preponderance of matter over anti-matter in our universe.
ON THE SPIN–ORBIT INTERACTION IN DIATOMIC MOLECULES. I
Authors: Kovács I.
Published: April 2011

The purpose of the present paper is to give further details of an investigation of the spin–orbit interaction in diatomic molecules. The first part of the paper deals with perturbations between states of odd multiplicity in a two-electron system. With the aid of the matrix elements which have been obtained, a comparison of the perturbations in the various components of a given state and in some cases a comparison of perturbations in two different states is possible. Also for certain cases it has been possible to establish relationships between the matrix elements which give the magnitude of the perturbations and experimentally measurable molecular constants of the perturbed states.
DISPLACEMENTS OF THE RADIANT POINT DURING THE AURORAL DISTURBANCE OF SEPTEMBER 22, 1957
Authors: Abbott W. N.
Published: April 2011

Three detailed photographs of the corona on a well-defined star field taken during the display of September 22, 1957, render possible determination of the position of the radiant point and measurement of its displacements. The photographs cover an interval of 21 minutes and the measured displacement, assumed to be continuous, divided by this interval gives an average rate of motion of about 12 minutes of arc per minute of time. The variation of the magnetic elements in the same interval is such as to indicate displacements of the magnetic zenith which, viewed from ground level, appear unrelated to the displacements of the radiant point.
THE REPRODUCIBILITY OF THE STEAM POINT
Authors: Berry R. J.
Published: April 2011

A steam-point apparatus and precision manometer have been constructed in connection with the realization of the International Temperature Scale at the National Research Council. By means of this apparatus the steam point may be realized to 0.0002 °C. with a reproducibility of 0.0001 °C; the difference is due to uncertainties in the physical constants involved.The manometer is capable of measuring pressures of from 0 to 85 cm. of Hg with a precision of 1 micron, using electrostatic capacitance detection of the mercury surfaces and end standards to determine the height. The steam boiler gives constant results for a wide variety of operating conditions and has been used to show the increase of temperature with increasing head of water vapor.The triple-point cells used in these experiments show a similar temperature change with change of immersion. It has been shown that a period of 1 to 3 days is required for them to establish temperature equilibrium, after which they are constant to within 0.0001 °C. The resistance thermometer used is extremely stable at the steam and triple points if it is carefully handled.
REFRACTIVE INDEX OF He4: LIQUID
Authors: Edwards M. H.
Published: April 2011

Changes in the phase refractive index n with temperature have been measured between 1.6 and 4.2° K at λ = 5462.27 Å, for liquid He4 at its saturated vapor pressure, using a metal optical cryostat and a Jamin interferometer. A novel adaptation of the Jamin interferometer has been made so that, in addition, an absolute determination of the group refractive index, nG, could be made using white light of "effective wavelength" 5595 ± 40 Å. When the dispersion correction is made, the phase index for the Hg green line at T55E = 3.700° K is n = 1.026124 ± 0.000035. The relative measurements have been adjusted to this value. The more than 200 experimental points show a random scatter of less than 5 × 10−6 in index. Using Kerr's density data the polarizability is thus (N0α) = (0.12454 ± 0.00021) cm3 mole−1 at λ = 5462.27 Å, for liquid He4 at 3.7 °K. Within experimental error (N0α) is found to be independent of temperature. Thus the refractive index data may be considered as a measurement of the liquid density and coefficient of expansion.The region near the λ-point is of special interest. The expansion coefficient determined from the refractive index, βn, may be represented within experimental error by 103βnI = +41.5 + 14.5 log|T−Tλ| for T > Tλ, from about 0.1° above Tλ to within 0.01° of Tλ; and by 103βnII = −1.5 + 14.5 log |T−Tλ| for T < Tλ, from about 0.1° below Tλ to within 0.002° of Tλ. This implies that the density–temperature curve has both a vertical tangent and a point of inflection at the λ-point; and that the maximum in density occurs about 0.001° above the λ-point.
MEASURED PHASE DISTRIBUTION IN THE IMAGE SPACE OF A MICROWAVE LENS
Authors: Farnell G. W.
Published: April 2011

Detailed measurements at a wavelength of 3.2 cm have been made of the phase distribution in the diffraction image produced by an aberration-free lens illuminated from a point source. The behavior of the phase of the electric field is shown by contours of constant phase (wavefronts) in the plane of the image space containing the axis and the H-vector of the radiating source. The region of the image space considered extends from the solid dielectric lens to a surface somewhat beyond the focus. Results are also shown of the phase distribution measured within about one wavelength of certain phase singularities which occur at the minima of intensity on the focal arc and on the axis. In general, there is very good agreement between plots of measured phase contours and plots of phase contours previously calculated from scalar diffraction theory.
PARTICLE EQUATIONS FROM NON-ASSOCIATIVE ALGEBRAS
Authors: Bourret Richard
Published: April 2011

Attention is called to the neglect of linear algebras not representable by matrices in the formation and study of possible relativistic wave equations. An eight-unit non-associative algebra of Cayley is used to construct a bilocal wave equation obeying a continuity equation and possessing invariance under bilocal gauge and (proper) Lorentz transformations. Mass terms are extracted from the equations and particle and interaction interpretations are briefly discussed.
FOUR-DIMENSIONAL ELECTROMAGNETIC RADIATORS
Authors: Shanks H. E. , Bickmore R. W.
Published: April 2011

This paper describes an entirely new and fundamental technique which has wide application to many fields of the antenna art as well as important system implications. The essence of this philosophy is the utilization of the time domain as an additional variable with which to control antenna radiation characteristics. One way to accomplish this is by periodically time-modulating one or more of the antenna parameters (aperture excitation, aperture shapes, frequency, phase distribution, aperture size, etc.) in a prescribed way. The result of this modulation is a radiation pattern whose characteristics are periodically changing as a function of time. By virtue of the periodic nature of the pattern fluctuations, an infinite number of independent information channels are available corresponding to the harmonic frequency components of the modulated patterns. Since each harmonic will, in general, have a different space factor associated with it, proper data processing can be utilized to provide simultaneous operation of a single antenna in a variety of modes. In addition, this technique allows synthesis of antenna radiation characteristics which might be unobtainable by conventional methods.
SOLID HARMONICS AS BASIS FUNCTIONS FOR CUBIC CRYSTALS
Authors: Betts D. D.
Published: April 2011

The various sets of basis functions useful in discussing cubic crystals must include sets of symmetrized combinations of powers of the co-ordinates ortho-gonalized over the cellular polyhedron. Such polynomials are here called solid harmonics. A study of the actual solid harmonics reveals the limitations of the spherical cell approximation. The solid harmonics can be used to develop a new method over the cellular polyhedron of the body-centered cubic lattice or of the face-centered cubic lattice.
TABLES OF THE MODIFIED BESSEL FUNCTIONS OF THE SECOND KIND FOR PARTICULAR TYPES OF ARGUMENT
Authors: Dempsey E. , Benson G. C.
Published: April 2011

Tables of the modified Bessel functions of the second kind Kn(z) for arguments z of the form (π/2)√q and (π/3)√q where q is an integer and for all integral and half-integral orders n in the range 0–10.5 are presented. For all but a small range of the argument the tables can be relied upon to the 10 figures given; in the omitted range an error of unity in the 10th place may occur. The tables should be useful for the computation of many lattice sums arising in the theoretical calculation of crystal properties.
CORRELATION STUDIES OF RADIO-AURORA, MAGNETIC, AND EARTH-CURRENT DISTURBANCES
Authors: Bhattacharyya B. K.
Published: April 2011

Correlation studies of the radar echo occurrence rate from aurora in half-hourly intervals at Ottawa, S and Sd components of the horizontal magnetic field H at Agincourt, and the disturbance diurnal variation of earth current at Crow River have been carried out. Short-time variations in auroral echo strength and moderate perturbations in H have also been correlated. The auroral echo occurrence rate seems to have a diurnal variation characteristic similar to that of H. It is found that auroral activity always precedes magnetic activity. The variation of the delay time between the two phenomena shows a local time dependence, being practically constant and quite small (0–15 minutes) before local midnight and increasing afterwards. This variation of the delay time appears to have a connection with reports of others regarding reversal of the direction of auroral ionization drift from west to east somewhere around midnight with subsequent magnetic perturbations which change from positive to negative.No definite conclusion could be reached regarding the relationship of earth current to other factors because of a practically random variation of cross-correlation coefficients from month to month.
ANALYSE DE LA BANDE 1–0 DU SYSTÈME 3Πi–3Σ− DE PH
Authors: Legay F.
Published: April 2011

The (1,0) band of the 3IIi-3Σ− system of PH has been photographed in absorption under high dispersion. Values for the rotational constants, the spin-coupling constant, and the vibrational interval [Formula: see text] of the 3Πi state have been obtained. A study of the A-doubling shows the existence of a perturbation in the 3Π0 state; it is not possible, however, to determine unambiguously the nature of the perturbing state.
A WORLD-WIDE STUDY OF THE DAILY VARIATION OF THE NUCLEONIC COMPONENT OF COSMIC RAYS
Authors: Katzman J. , Venkatesan D.
Published: April 2011

The semidiurnal component of the nucleonic intensity at Ottawa, Canada, is essentially a pressure effect for the 5-year period, 1955 to 1959. The diurnal variation is composed of the component due to pressure, and a component that may be attributed to an anisotropy of the primary cosmic-ray particles. The results are confirmed by a comparative study of the data from 15 stations between the geomagnetic latitudes 83 °N. and 73 °S.A world-wide barometric coefficient of −0.72% per mb was obtained from the semidiurnal component and this coefficient was used to correct the diurnal component at all the stations. The average corrected diurnal variation during the period of study common to all stations, August 1957 to October 1958, is 0.27% and occurs at 14 h 16 m solar time. There is considerable spread in both amplitude and phase angle amongst the various stations. The root mean square differences from the mean amplitude is ±0.05% and from the mean phase angle is ±10° (40 minutes in time). The difficulty of drawing definite conclusions about the anisotropy from short-term studies of individual stations is pointed out.
THE ELECTRICAL RESISTIVITY OF Mn3ZnC BETWEEN 4.2° AND 630° K
Authors: Swanson M. L. , Friedberg S. A.
Published: April 2011

The electrical resistivity of an alloy having approximately the composition Mn3ZnC has been measured between 4.2° and 630° K. From a high residual value the resistivity increases with temperature in a complicated way up to 550° K, becoming temperature independent above that point. Two anomalous regions are evident corresponding to the magnetic transitions occurring in this substance at ~240° K and ~450° K. The general features of the results are interpreted on the basis of a spin-disorder scattering picture.
ON THE TEMPERATURE DEPENDENCE OF PARAMAGNETIC RESONANCE IN THE CASE OF THE ISING MODEL
Authors: Lee Y. Y.
Published: April 2011

The adequacy of the approximation method used by McMillan and Opechowski in their theoretical study of the temperature dependence of the paramagnetic resonance line shape function is very difficult to ascertain for the case of a typical paramagnetic crystal. For this reason the approximation method has been investigated for the very simple case of the one-dimensional Ising model. Exact expressions for the line shape function of the model are compared with expressions obtained by the approximation method mentioned above. The agreement between the two expressions is found to be very good in general, and extremely good at very low temperatures.