bluuebunny/crossref_metadata_2025 huggingface dataset:
Charge Permutation and Dissociation of Molecular Ions by Impact with Neutral Molecules
Authors: Rourke F. M. , Sheffield J. C. , Davis W. D. , White F. A.
Published: January 2005

Resolved beams of ions with energies between 10 and 150 kev were passed through thin targets and the resulting beam analyzed as to momentum and energy. Equilibrium charge ratios were obtained for various ions after passing through thin films of Ni or organic polymer. Cross sections for several reactions of oxygen ions with gas targets were also obtained. For gaseous targets, some of the products of dissociative reactions exhibited two side peaks differing in energy from the normal peak. By relating this displacement to a velocity change produced by dissociation alone, the kinetic energy change involved in the dissociation of the ion can be calculated. Values for a number of cases are tabulated.
Measurement of the Recombination of H and OH in γ-Irradiated Aqueous Systems
Authors: Hardwick Thomas J.
Published: January 2005

Differences in radical and molecular yields in γ-irradiated light and heavy water solutions have been measured over the range of sulfuric acid concentration 0–0.8N.

Three new terms have been defined: GH* and GOH*, which represent the hydrogen atoms and hydroxyl radicals whose fate is to recombine to reform water; G—H2OI, which represents the gross number of water molecules decomposed into radicals. A model of radical formation and diffusion has been developed from which values of GH*, GOH*, and G—H2OI may be calculated from the experimental data.
Infrared Dispersion Due to the Asymmetric Stretching Vibration of CS2
Authors: Ferguson E. E. , Kagarise R. E.
Published: January 2005

Infrared dispersion data on liquid CS2 in the wavelength range 2–15 μ have been analyzed according to classical dispersion theory to yield both gas and liquid oscillator strengths for the asymmetric stretching vibration. The calculated gas intensity for this vibration is 7000×1010 cm—1 sec—1 (STP) as compared to directly measured values around 7500×1010. The intensity of the bending vibration of CS2 which has not yet been measured is inferred to be 275×1010 cm—1 sec—1. The CS bond dipole moment is calculated to be 1.24 debye which gives a quadrupole moment in reasonable agreement with experiment.
Photoconduction and Cis-Trans Isomerism in β-Carotene
Authors: Rosenberg Barnett
Published: January 2005

A discussion is given of some theoretical and experimental aspects of photoconductivity in β-carotene. It is shown that re-solidification of crystalline β-carotene results in the formation of a glass state which is photoconductive. The original all trans form is converted into a mixture of stereoisomers in the glass, and the appearance of the ``cis peak'' at 3500 A in the optical absorption spectrum is noted.

The photoconductive action spectrum of a sandwich-type cell of the β-carotene glass has a maximum in this cis peak region when the electrodes are biased in the forward rectifying direction. The interpretation given to this in terms of the triplet state theory of photoconduction is that intersystem crossing is more probable from the cis peak than from the first excited state. Some evidence exists from semiconduction and phosphorescence measurements that the active triplet state lies 3.0 ev above the ground state and thus falls in the region between the two singlet excited states. Thus, the temperature dependent Boltzmann factor may be largely responsible for the increase in intersystem crossing from the cis peak state.

The photocurrent in the back rectification direction is shown to be due to the light which is mostly transmitted through the glass and absorbed at the positive rear electrode. For strongly absorbed wavelengths the rectification ratio is 1.6×105.

The voltage dependence is described by the sum of a linear term and a three halves power term, the former of which dominates at low field strengths and low absorption of the exciting light. There is a linear dependence of the photocurrent upon intensity.

The similarity of the effects of cis-trans isomerization in phosphorescence and photoconductive studies strongly suggests that the intersystem crossing to the triplet state is the dominant element in common and is considered as strong corroborating evidence for the triplet state theory of photoconduction in organic materials.
Nuclear Magnetic Resonance Study of Boron Carbide
Authors: Silver A. H. , Bray P. J.
Published: January 2005

A nuclear magnetic resonance (NMR) study of boron carbide has been conducted using both powdered and single crystal samples. The resonance patterns for B11 were observed at several Larmor frequencies from 5.53 to 17.7 Mcps. Analyses of the spectra with the application of the quadrupole interaction show that there are three crystallographically nonequivalent boron positions, contrasted with the two positions given by x-ray structure determinations. Estimated quadrupole coupling constants for the 6h1 and 6h2 positions are given. The third position is assigned to 1b, previously believed to be occupied by carbon atoms. In the 1b positions, the quadrupole coupling constant of the B11 nuclei is 5.58±0.02 Mcps. Large variations in the width and shape of the resonance from the 1b atoms are explained by the presence of many small angle grains in the single crystal which produce variations in orientations of the local principal axis systems.
Anomalous Band Intensity in Fermi Resonance
Authors: Dixon R. N.
Published: January 2005

When two vibrational levels of a molecule are in Fermi resonance there is a ``sharing'' of band intensity in transitions to these levels. It is shown that in exceptional cases Fermi resonance can result in an overtone or combination band being stronger than the fundamental with which it is in resonance. The theory is applied to the electronic spectrum of the NCO radical, in which such an anomaly exists.
Magnetic Properties of Water Molecule
Authors: Das T. P. , Ghose T.
Published: January 2005

The mass susceptibility χ and proton magnetic shielding factor σ for H2O molecule are calculated using a localized electron pair LCAO MO wave function. The paramagnetic part of the susceptibility and a portion of the paramagnetic part of σ are calculated by a variational method used earlier for the H2 molecule. The relation of the present variational method to the methods employed by McGarvey and by Stephen is discussed in some detail.

The calculated value of χ is found to be —0.687×10—6 in very good agreement with the experimental value of —0.699×10—6. (In an earlier report [Bull. Am. Phys. Soc. Ser. II, 3, 372 (1958)] we stated the calculated value of χ erroneously as —0.692×10—6.) The calculated value of σ is, however, found to be only —0.85×10—5 in rather poor agreement with the experimental value of —2.97×10—5. The causes for this poor agreement are analyzed, and it is concluded that the main reasons are (1) use of a rather large ionic character (66%) for the OH bond obtained from a curve of electronegativity difference versus ionic character and (2) use of undistorted H-atom orbitals in the LCAO MO function. It is suggested that the calculated value of σ would improve in the right direction if the effective charge for the H-atom orbital were taken as greater than unity. The value of σ is recalculated with Ellison and Shull's ``approximate treatment'' wave function and found to be —1.31×10—5. The disagreement with experiment in this case is ascribed to cause (2).

Arguments are presented to show that more accurate values of σ for protons in a molecule can be obtained if in the Hamiltonian for the electrons the origin for the first-order perturbation term due to the magnetic field is taken at the centroid of the electronic charge rather than at any other point.
Twist in Lithium Fluoride Whiskers
Authors: Sears Gerald W.
Published: January 2005

Eshelby twists have been observed microscopically on very fine lithium fluoride whiskers grown from aqueous solution.
Absorption Spectra at 4°K of Single Crystals of Normal and Isotopically Substituted Sodium and Potassium Nitrates
Authors: Sayre Edward V.
Published: January 2005

Sharp line structure is observed in the low energy shoulder of the 3000-A absorption band of crystalline nitrates that have been cooled to 4°K. Single crystals of normal and of nitrogen-15 isotopically substituted sodium and potassium nitrates were examined spectrographically. Correlation between the spacings, polarization and orientation properties, isotope effect, and crystal field splitting of the spectra permitted their analysis. In terms of the D3h point symmetry of a free nitrate ion the excited electronic state is E′. This electronic configuration is one of three considered likely upon the basis of a LCAO molecular orbital treatment of the ion. The two asymmetric E′ vibrations of the ion predominantly contribute to the band structure. A large Franck-Condon shift, an extensive weakening of force constants, and the character of the excited vibrations indicate that the excited ion is planar but expanded with perhaps some, but not a great amount of asymmetric distortion. Predissociation appears at a level corresponding to a dissociation energy of 3.76 ev for the nitrate ion.
Some Measurements of Adsorption of Nitrogen and Oxygen on a (0001) Titanium Surface Using Low-Energy Electron Diffraction
Authors: George T. H. , Farnsworth H. E. , Schlier R. E.
Published: January 2005

Both nitrogen and oxygen chemisorb on the clean (0001) surface of titanium in crystalline monolayers having the same hexagonal symmetry and lattice constant as that of the titanium surface, but with different distances between the surface titanium plane and the gas planes. Adsorption as a function of exposure was determined for both gases. An average sticking coefficient for nitrogen at room temperature of about 1.8×10—5 was obtained.
Calculation of Energy Levels for Internal Torsion and Over-All Rotation. III
Authors: Herschbach Dudley R.
Published: January 2005

A general treatment of hindered internal rotation is given for molecules that can be regarded as a rigid symmetric top attached to a rigid frame which may be completely asymmetric. The perturbation approach developed in previous papers is simplified and extended by use of a method which relates the perturbation coefficients to the exact energy levels obtainable for the limiting case of two coaxial symmetric tops. Tables are given which provide the torsional energy levels and the perturbation coefficients through fourth order in the coupling between internal and over-all rotation. The tables apply to the lowest three groups of torsional states for a potential barrier of the form V(α)=12VN(1−cosNα)+12V2N(1−cos2Nα), where the periodicity N is arbitrary and O<̄V2N/VN<5%. The range of validity of the approximations is examined, and it is concluded that in most applications the previous second order treatment yields reliable values of the barrier height. Situations in which higher order corrections affect microwave spectra are illustrated by a reanalysis of the data for methyl silane and acetaldehyde.
Novel Perturbation Theory in Simple LCAO Treatment of Conjugated Molecules—Method of Perturbed Secular Determinant
Authors: Fukui Kenichi , Nagata Chikayoshi , Yonezawa Teijiro , Kato Hiroshi , Morokuma Keiji
Published: January 2005

A new method of perturbation theory is developed in the simple LCAO MO treatment of conjugated molecules. Several useful equations are derived, giving orbital energy, electron density, and bond order of the perturbed system.
Hydrogen Bond: An Experimental Verification of the Double Minimum Potential
Authors: Bell Charles L. , Barrow Gordon M.
Published: January 2005

The spectra of alcohols in the region of the first and second OH stretching overtone in solvents of various bonding strengths reveal a pair of solvent dependent absorption bands. These bands are shown to arise from an energy level splitting resulting from a double minimum in the potential energy curve for the proton. The form that the potential energy curve must assume to yield the observed spectra is such that the second minimum lies in the region of the v=2 vibrational energy level for ordinary hydrogen bonding situations. The higher overtone bands, particularly in strongly basic solvents, are characteristic of the broad potential well.

This observed splitting of the absorption bands of hydrogen bonded alcohols confirms the theoretical predictions of a double minimum potential energy function for the proton.
Validity and Consequences of Schreinemakers' Theorem on Ternary Distillation Lines
Authors: Korvezee A. E. , Meijering J. L.
Published: January 2005

The tangential behavior of distillation lines in a ternary mixture, as brought forward by Schreinemakers more than half a century ago, was denied some time ago by Redlich and Kister. We give another proof of the correctness of Schreinemakers' theorem. We define parameters Q0 governing the course of the distillation lines in each corner of the composition triangle. The Q0 values are, in principle, derivable from accurate binary boiling point curves. The occurrence of distillation lines with one or two points of inflection in a ternary system without complications from azeotropes or demixing is discussed at some length.
Deuterium Positions in Lanthanum Deuteroxide by Neutron Diffraction
Authors: Atoji Masao , Williams Donald E.
Published: January 2005

The deuterium positions in La(OD)3 have been determined by the neutron diffraction method. No hydrogen bonding was found in this structure. The close packing structure around the deuterium atom is characterized by the average distances of D—D = 2.29 A and D—O = 2.74 A. The infrared absorption spectra of La(OD)3 and La(OH)3 are briefly discussed.
Thermodynamic Properties of Some Boron-Oxygen-Hydrogen Compounds
Authors: Wilkins Roger L. , Altman Robert L.
Published: January 2005

The heat capacity, enthalpy, and entropy of gaseous B, B2, BH, BO, and B2O2 have been calculated in the ideal gas state from 0 to 6000°K by standard methods of statistical mechanics with available spectroscopic data.
Growth Mechanism for Graphite Whiskers
Authors: Sears Gerald W.
Published: January 2005

A mechanism is described which gives rise to the scroll habit which has been observed for graphite whiskers. A supersaturation region exists which would favor the postulated growth mechanism.
Proton Spin Relaxation in Aqueous Solutions of Paramagnetic Ions. II. Cr+++, Mn++, Ni++, Cu++, and Gd+++
Authors: Morgan L. O. , Nolle A. W.
Published: January 2005

Nuclear magnetic relaxation times for protons in dilute aqueous solutions of chromic, manganous, nickel, cupric, and gadolinium ions were measured in the frequency range 1.9 to 60 Mc/sec. Results were interpreted in terms of Solomon's formulation of electron-nuclear dipole-dipole interaction and Bloembergen's expression for scalar coupling of electron and nuclear spins. In large magnetic fields relaxation times were found to be shorter than those expected on the basis of low field values, suggesting that the effective ion magnetic moments, electron spin relaxation times, and/or electron-nuclear spin exchange constants are field-dependent.
Statistical Mechanics of Rigid Spheres
Authors: Reiss H. , Frisch H. L. , Lebowitz J. L.
Published: January 2005

An equilibrium theory of rigid sphere fluids is developed based on the properties of a new distribution function G(r) which measures the density of rigid sphere molecules in contact with a rigid sphere solute of arbitrary size. A number of exact relations which describe rather fully the functional form of G(r) are derived. These are based on both geometrical considerations and the virial theorem. A knowledge of G(a) where a is the diameter of a rigid sphere enables one to arrive at the equation of state. The resulting analytical expression which is exact up to the third virial coefficient gives the fourth virial coefficient within 3% and the fifth, insofar as it is known, within 5%. Furthermore over the entire range of fluid density, the equation of state derived from theory agrees with that computed using machine methods. Theory also gives an expression for the surface tension of a hard sphere fluid in contact with a perfectly repelling wall. The dependence of surface tension on curvature is also given. The expressions obtained correlate nicely with those adduced by other thermodynamic and statistical mechanical theories. They also suggest that macroscopic consideration on surface tension can sometimes be successfully extrapolated to molecular dimensions.
Ligand Influence upon Radial Wave Functions
Authors: Belford R. Linn , Karplus M.
Published: January 2005

The influence of the ligand field upon the radial distribution function for the 3d orbitals of a transition metal complex ion has been investigated. A simple one-electron approximation was used for the metal ion and a point-charge model was employed for the ligands. Exact numerical solutions of the resulting radial equations were obtained and compared with one-parameter variation functions. For reasonable ligand charges and distances, the displacements in orbital energies and transition frequencies are found to be smaller than the errors in current theories. However, the differential expansions and contractions in the orbitals are sufficiently large to produce significant changes in certain radial integrals.
Effect of Catalyst Size in Heterogeneous Nucleation
Authors: Maurer R. D.
Published: January 2005

Light scattering and optical absorption have been used to study a photosensitive glass in which a gold colloid nucleates further crystallization. The depolarized component of the scattered light at 90° begins to increase abruptly after an elapsed time interval in the precipitation. This increase is attributed to a rapid increase in the nucleation catalysis by the gold colloid. The elapsed interval represents the time necessary for the gold colloid to grow to a size that is effective. In agreement with this, very high exposures, which produce very small colloid particles, result in little crystallization. The colloid size necessary for nucleation catalysis appears to be of the order of 80 angstroms. While this size may be connected with the critical size of the crystals that form on the gold colloid, an alternative explanation based on the curvature of small particles is also proposed.
Magnetic Properties of Some Iridium Complexes
Authors: Norman Vello , Morrow J. C.
Published: January 2005

The magnetic susceptibilities of a series of iridium complexes have been measured over a temperature range from 78°K to room temperature. K2IrCl6, (NH4)2IrCl6, (NH4)2IrBr6, and (CH3NH3)2IrCl6 follow the Curie-Weiss relationship approximately. The susceptibilities of (C5H6N)2IrCl6 and (Φ4As)2IrCl6 do not yield straight line 1/χM versus T°K plots. Ir(C5H5N)2Cl4 was found to be diamagnetic.
Unique Luminescences of Dry Chlorophylls
Authors: Fernandez Jose , Becker Ralph S.
Published: January 2005

Dry chlorophylls a and b in a rigid glass hydrocarbon solvent have intense emission at 7550 A and 7330 A, respectively. In each case, the room temperature absorption spectra show the presence of a band shoulder on the long wavelength side of the main red band. Both the emission and the absorption bands disappear in the presence of hydroxyllic solvents. The absorption and emission are interpreted as n-π* singlet and n-π* triplet transitions, respectively. The lifetime of the n-π* triplet emission in chlorophyll a is estimated to be 10—3 second. Cu chlorophyll b has an intense phosphorescence at 8740 A with a lifetime of less than 10—4 second. The differences in the room temperature emission spectra for chlorophylls a and b are discussed.
Crystal Constituent Effects. III. Partition of Ni++
Authors: Pastor R. C.
Published: January 2005

A phenomenological treatment of partition of a solute ion between the saturated solution and the equilibrated crystal is given. The description is applicable to the experimental results obtained with Ni++ as the solute ion in (Zn, Ni)SiF6 and in (Mg, Ni)SiF6 solutions. Crystal coring in mixed crystals is discussed from the standpoint of partition coefficients. The partition coefficient for Ni++ was also measured by using other host salts isotypic with the fluosilicate.
Theory of the Phase Transition between Helix and Random Coil in Polypeptide Chains
Authors: Zimm B. H. , Bragg J. K.
Published: January 2005

The transition between the helical and randomly coiled forms of a polypeptide chain is discussed by reference to a simple model that allows bonding only between each group and the third preceding. Two principal parameters are introduced, a statistical parameter that is essentially an equilibrium constant for the bonding of segments to a portion of the chain that is already in helical form, and a special correction factor for the initiation of a helix. A third parameter which specifies the minimum number of segments in a random section between two helical portions has only a minor effect on the results. The partition function for this model is handled in two alternative ways, either as a summation suitable for short chains, or in terms of the eigenvalues and eigenvectors of a characteristic matrix; the latter is more suitable for long chains. A transition from the random to the helical form is encountered as either the bonding parameter or the chain length is increased. The critical value of the bonding parameter is unity for long chains, while the sharpness of the transition depends on the initiation parameter.

Depending on the values of the bonding parameter and the chain length, one of the following configurations dominates: random coils, single helices with occasional disorder at the ends, and for longer chains, helices occasionally broken by random sections. In rather narrow transition regions, mixtures of these forms may be found. A diagram is given that displays the relationships of these forms.

The theory is compared with published data on polybenzyl-glutamate with fair agreement.
Molecular and Crystal Structure of B8Cl8. II. Solution of the Three-Dimensional Structure
Authors: Jacobson Robert A. , Lipscomb William N.
Published: January 2005

With only the information that B and Cl are present in the approximate ratio of 10 to 9, the molecular structure of B8Cl8, a new boron chloride, has been determined from single crystals by x-ray diffraction methods. The chlorine positions, solved by a point-by-point, three-dimensional Patterson superposition method, enabled the boron atoms to be located from electron density maps. The boron atoms form a dodecahedron with triangular faces and D2d symmetry. One chlorine atom is attached to each boron atom at an average distance of 1.70 A. The shortest boron-boron distance is 1.78 A. The over-all agreement factor is R=Σ| |F0|−|Fc| |/Σ|F0|=0.17.
Microwave Spectrum and Structure of Perrhenyl Fluoride
Authors: Lotspeich J. F. , Javan A. , Engelbrecht A.
Published: January 2005

Rotational absorption lines of the symmetric-top molecule ReO3F have been observed in the K-band regions of 21 400 and 28 500 Mc, with a Stark modulation spectrometer designed specially to accommodate this and other chemically reactive molecules The spectrum exhibits a hyperfine structure arising from interaction of the Re nuclear electric quadrupole moment with the surrounding charge. The hfs pattern establishes the Re nuclear spin as 5/2 and yields a quadrupole coupling constant eqQ (Re187) = (—48.4±1.3) Mc for the ground vibration state. Additional groups of lines associated with molecular states of vibrational excitation were also present. Of the six normal vibration frequencies, three were sufficiently low to contribute an observable fraction of molecules to their excited states: one non-degenerate, ν3 (a1), and two doubly degenerate, ν5 (e) and ν6 (e). The corresponding rotation-vibration and l type doubling constants were measured to be α3 = (+12.30±0.06) Mc, α5 = (—10.91±0.06) Mc, ql5 = (16.31±0.25) Mc, α6 = (+2.52±0.06) Mc, ql6 = (5.00±0.24) Mc. Strong dependence of quadrupole coupling on molecular vibration was observed, the values of eqQ (Re187) being —27, —35, and —58 Mc respectively in the singly-excited states ν3, ν5, and ν6. Comparative measurements of line intensities relative to those of the ground vibration state yield the following approximate values for the three lowest normal vibration frequencies: ν3 = (325±40) cm—1, ν5 = (410±25) cm—1, ν6 = (345±40) cm—1. Measurements of the Stark effect in ReO3F give as the dipole moment of this molecule a value μ = (0.85±0.05) debye.

Precise determination of molecular structure was effected from frequency measurements of lines belonging to the slightly asymmetric top ReO216O18F. The results give Re–O = (1.692±0.003) A, Re–F = (1.859±0.008) A, F–Re–O = 109° 31′±16′. Comparison is made between these and the known values of two other structurally similar molecules, ReO3Cl and MnO3F.
Quadrupole Coupling and Bond Structure in ReO3F, ReO3Cl, and MnO3F
Authors: Lotspeich J. F.
Published: January 2005

A theoretical explanation is offered to account for the magnitude and sign of the quadrupole coupling constants in ReO3F, ReO3Cl, and MnO3F. Subject to the requirement that the valence electron bonding orbitals of Re and Mn have a tetrahedral configuration, a combination of s, p, and d atomic orbitals is chosen which tends to minimize the energies of bond formation. Results of the analysis reveal that, in order to account for the observed quadrupole couplings, the effect of atom core polarization must be considered. It is shown in particular that the contribution to the electric field gradient at the Re nucleus from the polarized electron core is more than 25 times that of the external polarizing ions themselves.

Comparison of the quadrupole coupling in ReO3F with that of atomic Re shows that the amount of unbalanced p electron along the molecular symmetry axis is nearly zero and thus provides a reasonable explanation for the pronounced dependence of eqQ(Re) on the state of molecular vibration.
Absorption Spectrum of NiCl2 in Molten LiCl/KCl
Authors: Sundheim Benson R. , Harrington George
Published: January 2005

The absorption maxima in the spectra of NiCl2 in molten LiCl/KCl are discussed from the point of view of the ligand field theory. It is concluded that the nickel ion is surrounded by four chloride ions in a nearly tetrahedral arrangement. Variations in the intensity of one of the bands gives a sensitive indication of the degree of distortion of this structure.
Dynamical Theory of Electrosedimentation
Authors: Peterlin A. , Ribarič M.
Published: January 2005

Besides the steady-state solution the time dependence of particle distribution in the cylindrical cell in both limiting cases, t→0 and t→∞, is given. The initial rise of electric capacity and the asymptotic approach to the steady state yield information concerning the diffusion constant of the suspended particles (weight average and number average). The dependence of the capacity change on the applied field permits, at least in principle, the determination of particle size averages of increasing order.

The experimental arrangement can be greatly improved by using suspension liquids having higher dielectric constant than the particles, e.g., polar liquids and nonpolar particles. The field then drives the particles away from the central wire into areas of lower field strength. In such a case the concentration in no part of the cell noticeably surpasses the initial concentration and it is therefore much easier to remain in the linear concentration range. A rough estimate indicates that the method may be promising for suspensions of compact particles of M∼106 where a rather simple measurement yields the average size. With true solutions of linear macromolecules the situation is much less favorable because the large extension of the coils requires so much lower concentrations.
Statistical Interpretation for Abnormal Rotation of OH* Split from H2O2 by Electron Impact
Authors: Horie T. , Watanabe S. , Kurata K.
Published: January 2005

The angular momentum distribution of OH* split from H2O2 by electron impact or ultraviolet irradiation is quite abnormal in appearance. A statistical interpretation is presented of the relative population of the excited rotational levels of OH* in the dissociation process of H2O2 into two hydroxyl radicals. The phase volume is calculated under the constraints of the conservation of energy, momentum, and angular momentum by the method using delta and step functions. A discrepancy which takes place beyond K=24 between the calculated curve and the observational plots is attributed to the predissociation of OH*.
Magnetic Investigations of Spin-Free Cobaltous Complexes. I. Tetrahalo Cobalt(II) Ions
Authors: Holm Richard H. , Cotton F. Albert
Published: January 2005

The magnetic susceptibilities of six spin-free tetrahalo complexes of bivalent cobalt, CoX4—2 (X=Cl—, Br—, I—), have been investigated over a temperature range and found to exhibit satisfactory dependence on the Curie-Weiss law. The magnetic moments were found to be in the order predicted by crystal field theory, viz., I—>Br—>Cl—, whereas previously reported moments for these ions are in the reverse direction. The origin of this trend is briefly discussed. Evidence obtained from the magnetic measurements is offered in support of the assignments by Ballhausen and Jørgensen and by Orgel of the crystal field bands in CoCl4—2.
Triatomic Linear Molecules Containing Carbon and Oxygen, Sulfur, Selenium, or Tellurium. III. Absolute Intensity of the σ3 Band of CSe2
Authors: Wentink T. , Bauer S. H.
Published: January 2005

The rate of change of the axial dipole moment with asymmetric bond extension in carbon diselenide has been computed from the measured gas phase infrared absorption intensity of the σ3 fundamental band. The absolute intensity was measured by the pressure-broadening technique, using nitrogen or air as the foreign gas. The magnitudes of dμ/dr for CO2, OCS, CS2, and CSe2 are compared. Also, the absorption intensity of the σ3 band of CSe2 dissolved in CS2 was measured.
Molecular Constants of Carbonyl Sulfide and a Coriolis Perturbation
Authors: Saksena G. D. , Wiggins T. A. , Rank D. H.
Published: January 2005

The band origins and the changes in B and D for five bands of carbonyl sulfide have been measured. The highly precise values obtained are the result of precise infrared measurements used in conjunction with microwave results. The changes in B for the 002 and 003 bands agree with the reported value of α3 from microwave measurements. The other bands, members of resonating polyads, have anomalous values of ΔB. The ΔD values also reflect this resonance.

A Coriolis rotational perturbation in the 003 band has been observed and analyzed.
Calculation of Reaction Profiles behind Steady State Shock Waves. II. The Dissociation of Air
Authors: Duff Russell E. , Davidson Norman
Published: January 2005

A numerical integration procedure has been used to investigate the reaction profile behind strong shock waves in air. The Mach number range from 8 to 15 was covered; the initial temperature was 300°K; and the initial pressures were 1 and 10 mm Hg. The dissociation reactions for O2, N2, and NO were considered along with the ``shuffle'' reactions N+O2⇄NO+O and O+N2⇄NO+N. No ionization reactions were included. Above Ms=10, the calculations show a pronounced transient maximum in the NO concentration. In addition, the rates of change of concentrations at constant volume of all species except O2 change sign under certain conditions. Several additional calculations were made which included an approximate treatment of the effects of a finite rate of vibrational excitation of O2 and N2. These calculations suggest that even at Ms=15, the vibrational excitation reactions have only a limited effect on the reaction profile. A calculation of the reaction profile for air at high pressure diluted with a large excess of inert gas at 3000°K showed that the Zeldovich mechanism approximately describes the production of NO under these conditions even though it fails completely for undiluted air at high temperatures.
Spectral Study of a Visible, Short-Duration Afterglow in Nitrogen
Authors: Beale G. E. , Broida H. P.
Published: January 2005

In the discharge products of rapidly flowing, pure nitrogen at pressures between 4 and 15 mm Hg, an afterglow differing from the usual Lewis-Rayleigh afterglow has been found to occur approximately 5 milliseconds after the discharge. This pink-colored afterglow persists for about 2 milliseconds and is both preceded and followed by the usual yellow glow of active nitrogen. In the visible and near ultraviolet, this short-duration glow is characterized by strong emission of N2+ (B 2Σu+−X 2Σg+) and N2 1st positive (B 3Πg−A 3Σu+) bands and weak emission of N2 2nd positive (C 3IIu—B 3IIg) bands. The vibrational intensity distributions of the bands are similar to that of the discharge, including strong emission from vibrational levels above the predissociation limit of the B 3IIg state. The existence of this afterglow shows the presence of highly energetic species other than nitrogen atoms after the discharge.
Thermodynamic Study of InSb with a Mass Spectrometer
Authors: DeMaria G. , Drowart J. , Inghram M. G.
Published: January 2005

The gaseous molecules in thermodynamic equilibrium with solutions of indium and antimony have been determined and their partial pressures measured. From these measurements, partial molar free energies, and heats and entropies of solution have been calculated. In addition, for the gaseous molecules the following dissociation energies have been obtained: ΔH0∘ (Sb–Sb)=70.6±1.5 kcal/mole,ΔH0∘ (In–In)=22.4±2.5 kcal/mole,ΔH0∘ (In–Sb)=35.4±2.5 kcal/mole,ΔH0∘ (InSb–Sb)=66.7±2.5 kcal/mole.
Fluctuations and the Limit of Validity of the Debye-Hückel Theory
Authors: Frank Henry S. , Thompson Peter T.
Published: January 2005

An equation derived by Fowler and by Kirkwood has the general form of the Poisson-Boltzmann equation of the Debye-Hückel theory, but shows the latter to fall short of rigorous correctness through omission of two terms proportional, respectively, to the part played by a cloud ion in inducing charge density and to the sum of the mean-square fluctuations of the components of field strength. It seems likely that these correction terms would disappear or cancel for the case of an infinitely fine-grained ion cloud in an idealized continuous-dielectric solvent. By proceeding on this hint, it is shown that the equations of the Debye-Hückel theory contain within them the implication that ψ, ρ, E etc., are nonfluctuating and that the Debye-Hückel ion cloud does in fact approach infinite fine-grainedness in an appropriate sense as infinite dilution is approached. The theory, and the equations to which it leads, can thus be interpreted as being rigorously correct in the limit of infinite dilution but only in this limit. As concentration increases, failure of fine-grainedness begins to introduce errors into the equations and it is concluded that these become catastrophic and lead to a breakdown of the Debye-Hückel formalism at a concentration c0, where the thickness of the ion cloud 1/κ, equals l̄, an average distance apart of nearest-neighbor ions. For 1–1 solutes in water at 25°C, c0≈10—3 moles/l, and for higher valence-types, or lower dielectric constants, it is still smaller. These results may be paraphrased by the statement that the Debye-Hückel theory is a theory of long-range interactions and fails when nearest-neighbor interactions begin to dominate. The suggestion emerges that for c̄>c0 the electrostatic behavior of the ion cloud may be related to l as a characteristic length. This suggestion receives support from the observed fact that logf± seems typically to be linear in c⅓ in the concentration range just above c0.
Thermodynamic Functions of Some Chlorine Compounds
Authors: Potter Robert L.
Published: January 2005

The thermodynamic functions of Cl(g), Cl2(g), HCl(g), and ClF(g) have been calculated for these substances in the ideal gas state from 273.15°K to 5000°K by standard methods of statistical mechanics using available spectroscopic data.
Near Infrared Spectra of Crystalline Alkali Hydroxides
Authors: Buchanan Robert A.
Published: January 2005

The technique of melting alkali hydroxides between alkali halide plates has been used to obtain the near infrared absorption spectra of LiOH, LiOD, NaOH, NaOD, KOH, and KOD. Complicated combination band structure is observed in NaOH similar to that observed previously in LiOH, Ca(OH)2 and Mg(OH)2. The deuterated spectra of LiOH and NaOH indicate that both translational and librational (or rotational) modes couple to the fundamental OH— ion vibrations. Fundamental frequencies of 3611±4 cm—1 and 2654±2 cm—1 are observed for KOH and KOD, respectively. Reactions of the alkali hydroxides with certain alkali halides are observed.
Apparent Activation Energy and Frequency Factor for a Process Involving Competing Mechanisms
Authors: Nicholas J. F.
Published: January 2005

If a process involves competing mechanisms, each of which individually obeys Arrhenius' equation, the dependence of the combined rate on temperature is in general not of this type. However, apparent activation energies and frequency factors can be measured. In this paper, several sets of mechanisms distributed with respect to activation energy are considered and the apparent activation energies and frequency factors are calculated in terms of the parameters of the distributions. The results for a two-peak distribution, a flat distribution, and a truncated exponential distribution are given analytically and graphically. A simple approximate method is described for determining the apparent activation energy in some cases. Some remarks are made about the ``compensation effect.''
LCAO Wave Functions for Hydrogen Fluoride with Hartree-Fock Atomic Orbitals
Authors: Karo Arnold M. , Allen Leland C.
Published: January 2005

Accurate Hartree-Fock fluorine functions and an exponential Slater 1s hydrogen orbital have been used as basis functions in a conventional SCF LCAO—MO treatment of the HF molecule at five internuclear distances. Comparison with Hartree-Fock calculations for the isoelectronic F— and Ne systems gives a qualitative indication that a rather close approximation to the true molecular Hartree-Fock solution for HF has been achieved. Configuration interaction has been included with the restriction that the 1σ orbital remains filled. Molecular energies, dipole moments, and other molecular quantities are evaluated and compared with experimental results and with other theoretical work.
Gas of Hard Nonattracting Spheres
Authors: Rice O. K.
Published: January 2005

When a gas or hard nonattracting spheres is compressed it can go over into a densely packed random arrangement or a regular arrangement which becomes close packed at high densities. To these arrangements correspond two branches of the equation of state (pv/kT vs v). Though it is not possible to get an exact expression for the equation of state, the curves are fairly well determined by the application of certain general considerations concerning the entropy, by a general form for the random branch of the equation of state, and by some interpolations; certain geometrical factors having to do with the spherical shape of the particles are of some importance. Curves so obtained are compared with the results of some published machine calculations. The possibility of a first-order transition between the two branches is considered, and the position of such a transition, if it occurs, is roughly located.
Strong Coupling in Nuclear Resonance Spectra. II. Field Dependence of Some Unsymmetrical Three-Spin Spectra
Authors: Fessenden R. W. , Waugh J. S.
Published: January 2005

Magnetic resonance spectra are calculated and compared with experiment for the vinyl group of styrene, 2,4-dichloroaniline, and 2,5-dichloroaniline at various magnetic field strengths. Some simple rules are presented which facilitate the determination of chemical shifts and coupling constants, including the signs of the latter. One of the spectra illustrates the occasional necessity for experiments at more than one field strength if the parameters are to be determined unambiguously. In each case the shielding and coupling constants are found to be field-independent within experimental accuracy.
Ferroelectric Behavior of Thiourea
Authors: Goldsmith G. J. , White J. G.
Published: January 2005

The dielectric constant, and the ferroelectric, pyroelectric, and piezoelectric properties of thiourea crystals have been measured in the temperature range 90°K to 300°K. At least three dielectric anomalies are found at 169°K, 177°K, and 202°K, the lowest of these corresponding to a pronounced discontinuity. The crystals are ferroelectric in two regions, below 169°K and between 176°K and 180°K. Substitution of deuterium for hydrogen causes the anomalies to move upwards in temperature by 16°, 16°, and 11°, respectively. The crystal structure has been determined in detail at 120°K in the lower ferroelectric region. The transition from the antiferroelectric room temperature structure to the ferroelectric state is accomplished by small rotations of the molecules such that two of the molecules in the crystal unit cell have tilts to the ferroelectric b axis appreciably different from the other two, and the resultant of the molecular dipoles along [010] is no longer zero. The ferroelectric reversal is thus easily accomplished by interchanging the tilts of the two pairs of molecules.
Theoretical Investigations on the Light Scattering of Colloidal Spheres. VII. Dissymmetry in Unpolarized and Polarized Light
Authors: Heller Wilfried , Nakagaki Masayuki
Published: January 2005

Light scattering of nonabsorbing colloidal spheres is calculated, on the basis of the Mie theory, for the angles of observation, γ, of 45° and 135°. The parameters considered are α = 0.2 (0.2) 15.2 and m = 1.20. The scattering ratio is derived for both angles, for both unpolarized and linearly polarized light. Numerical data are given for the dissymmetry in both unpolarized and polarized light. A graph is included for an easy, approximate calculation of dissymmetries at any m values within the range 1.00–1.25. The maxima and minima of light scattered at 45° and 135° and of the dissymmetry are discussed, and a simple equation is given for deriving the α values at which they occur if m→1.0. The results are compared with alternate ones derived from the Rayleigh-Gans and Debye equations.
Equilibrium Properties of a Multicomponent Ionized Gas
Authors: Harris Gilda Maki
Published: January 2005

A method has been developed for the calculation of the equilibrium properties of an ionized gas consisting of many nuclear and molecular species. An essential feature of the present calculation is that it explicitly considers more than one ionic species per atom and therefore applies to partially ionized atoms and molecules. Free and bound electrons are distinguished by counting as bound electrons all those in the ground state of each ionic species. Molecular species with internal degrees of freedom are also included. The additivity of kinetic and potential energy is assumed, a classical electrostatic potential of interaction is used, and electron degeneracy is included only in the kinetic energy terms. The Helmholtz free energy of the system is minimized with respect to the concentration of each species assumed present, thus determining the equilibrium composition of the system as a function of temperature and volume. The thermodynamic quantities of interest are then calculated for an appropriate temperature-volume grid. This method thus allows the effect of the variation of composition on the equation of state to be determined, as well as the delineation of regions in PVT space where the electron degeneracy and electrostatic interaction each becomes important. The present model is applied to a system of particles arising from the hydrogen molecule.
Comparison of High-Energy and Ultraviolet-Radiation Induced Luminescence in Liquid Systems
Authors: Lipsky Sanford , Burton Milton
Published: January 2005

Luminescence induced by Co60-gamma excitation of some organic solvent-solute pairs has been compared with 2537 A excitation as to dependence of intensity on solute concentration and on concentration of an added quencher. The solutions studied were 1,6-diphenylhexatriene in benzene, p-terphenyl in benzene, and p-terphenyl in toluene. The quencher was bromobenzene. The energy-transfer parameter Q of the Kallmann-Furst theory and the quenching constant were obtained for each of the systems. Within an estimated experimental error of about 5%, Q was unaffected by change in source of excitation. The efficiency of quenching was found to be greater for Co60-gamma than for uv excitation for the two systems involving p-terphenyl. With diphenylhexatriene as solute, however, the quenching constant was unchanged. These results argue against a mechanism of energy exchange involving charge transfer. The high rates of transfer and quenching are consistent with a picture of the solvent involving the existence of small ordered regions within which exciton transfer can occur so that the entire region is viable to attack by a foreign molecule with resultant quenching or energy transfer.
Computation of Asymmetric Rotator Constants from Energy Moments. III. First-Order Centrifugal Stretching Effects
Authors: Parker Paul M. , Brown L. Carlton
Published: January 2005

Further expressions are developed which relate the parameters of the asymmetric rotator to experimental data through moments of the energy levels. The expressions developed here apply to an asymmetric rotator system described by a Hamiltonian which includes terms allowing for first-order centrifugal stretching effects. A criterion for the applicability of the first-order theory is given.
Growth of Aluminum Oxide Whiskers by Vapor Deposition
Authors: DeVries R. C. , Sears G. W.
Published: January 2005

The growth of aluminum oxide crystals has been observed in progress at 80X magnification with a stereo-microscope. Hydrogen is passed over an aluminum-oxide rod heated by a surrounding tungsten coil. As the hot products diffuse to the cooler region around the reaction zone, the reaction reverses to grow aluminum-oxide crystals. This system is of particular interest since it allows the screw dislocation theory of crystal growth to be examined in great detail on a high-temperature system.
Angular Dependence of Electron-Coupled Proton Interactions in CH2 Groups
Authors: Gutowsky H. S. , Karplus Martin , Grant D. M.
Published: January 2005

Experimental and theoretical studies have been made of the dependence upon HCH angle of the electron-coupled proton-proton interactions in CH2 groups. A valence-bond approximation is used in the theoretical treatment which predicts that the coupling constant AgemHH decreases from 32 cps to 0 cps for HCH angles of 100° to 125°. For angles greater than 125°, AgemHH is predicted to be negative. Experimental values of AgemHH have been obtained from analyses of the proton magnetic-resonance spectra of a number of compounds, including several partially deuterated species. Insofar as the HCH angles are known in these compounds, there is good agreement between the theoretical and experimental coupling constants, especially for angles smaller than 120°, for which AgemHH changes more rapidly with angle. Moreover, a negative value is found experimentally for AgemHH in vinyl bromide at an HCH angle which is approximately that at which the theory predicts the coupling to become negative. The substituted ethylenes constitute the largest group of compounds studied experimentally. In them, AgemHH has been found to vary from 3.2 cps to —1.8 cps, while the Ac isHH values range from 6.9 cps to 12 cps and the AtransHH from 14.3 cps to 18.4 cps. The various results presented indicate that the value of the coupling constant can serve as a measure of the HCH angle. However, further work is needed to confirm the reliability of the method and investigate the effects of substituent perturbations.