bluuebunny/crossref_metadata_2025 huggingface dataset:
Description of Crystallite Orientation in Polycrystalline Materials Having Fiber Texture
Authors: Roe R.-J. , Krigbaum W. R.
Published: January 2005

The distribution of plane-normal orientations in a polycrystalline sample can be investigated by x-ray diffraction measurements. Our problem is to deduce from such a set of data the maximum amount of information concerning the distribution of crystallite orientations within the sample. We restrict our attention to samples having fiber texture. The plane-normal distribution function is expanded in a series of Legendre polynomials, the coefficients of which are to be evaluated from the experimental diffraction data. The crystallite distribution function is expanded in a series of spherical harmonics, the coefficients of which may be obtained by the solution of a set of simultaneous linear equations. Certain simplifications arising from symmetry within the unit cell, or in the crystallite distribution, are examined. The effects of series termination errors are investigated, and relations are presented which permit one to estimate the number of terms which will be required to achieve a specified degree of accuracy.

If diffraction from a particular plane is too weak to measure, the present treatment permits the construction of its plane-normal distribution from diffraction data for other planes. Also, the effect of overlapping reflections can be accounted for. Finally, one can obtain information concerning the distribution of orientations for a subset of crystallites in the sample, for example, those having a specified c-axis orientation.
Thermal Dissociation of Hydrogen
Authors: Moore George E. , Unterwald F. C.
Published: January 2005

This paper describes ``thermal dissociation'' or ``atomization,''H2⇌2 H,on a Mo or W catalyst, from 1200° to 2500°K. We emphasized transient behavior of individual species (especially H) caused by changing catalyst temperature. Reaction rates, and equilibria derived from them, confirm Langmuir's results of 50 years ago, and disagree with more recent authors who published reaction rates 200-fold faster. These authors did not emphasize chemical identification of both reactants and products, but attributed a measured decrease of total pressure to H, produced as in (1) and abstracted either chemically or by refrigeration. Reactions unrelated to atomization can decrease total pressure.

Transient behavior above 1200°K was dominated by diffusion; this suggests that neither surface atomization mechanism usually favored is important. Our transient methods permit evaluation of parameters fundamental for diffusion and for solution of hydrogen in W or Mo, from 10—7 to 10—4 Torr, well below the range of the Fowler—Smithells theory. These may be the first quantitative diffusion data published for the tungsten—hydrogen system. Using D=D0 exp(—Q/RT) we obtained: TungstenMolybdenumD at 1985∘K2.2×10−82.8×10−7D07.25×10−4Q41.5 kcal/mole H2Heat of solution64 kcal/mole H216–22 kcal/mole H2 (1360–1980∘K)SolubilityOne atom of H per 400 atoms of W at 2440∘ and 1.2×10−4 TorrOne atom of H for 104 atoms of Mo at 1985∘K and 10−6 Torr
Eye Melanin Free Radical Kinetics and Mechanism in Relation to the Roginsky—Zeldovich (or Elovich) Equation and the Adsorption of Oxygen by Semiconductors
Authors: Cope Freeman W.
Published: January 2005

Eye melanin free radical decay was previously shown to conform to an equation derived from a postulate that the rate-limiting step was electron conduction across the liquid—solid interface at the surface of the melanin particle. It is shown here that this equation closely approximates the Roginsky—Zeldovich (or Elovich) equation for oxygen adsorption on inorganic semiconductor solids, which provides two convenient graphical criteria for this type of kinetics. Because the behavior of charge carriers is essentially similar in liquids and solids, it is believed that this derivation of the Roginsky—Zeldovich (or Elovich) equation is also applicable to phenomena at solid—solid interfaces in inorganic semiconductors. The similarity between the kinetics of melanin free radicals and semiconductor oxygen adsorption, together with previous experimental data indicating a dependence of melanin radical concentration on oxygen concentration, suggests that the eye melanin free radical process may involve oxygen adsorption with electron transfer across the surface of the melanin particle.
Hydrodynamic Alignment of Rodlike Macromolecules During Ultracentrifugation
Authors: Peterson James M.
Published: January 2005

The effect of intermolecular hydrodynamic interaction on the alignment of rodlike macromolecules during ultracentrifugation is presented. It is shown that the resulting effect is extremely small in magnitude, and in fact predicts a decrease in observed sedimentation coefficient with applied field, which is contrary to experimentally observed properties of the sedimentation coefficient. The intermolecular hydrodynamic interaction mechanism is thereby shown to be unimportant in explaining the origin of this phenomenon. A possible alternative mechanism involving tactoids is briefly discussed.
Excluded Volume Effect in Polymer Chains. II. Properties of Restricted Chains on a Diamond Lattice
Authors: Smith Richard P.
Published: January 2005

A study has been made of nonintersecting chains of N bonds on a diamond lattice by exact enumeration for small N and extrapolation of the results to large N. For the number of configurations, an improved extrapolation method is given, along with data to N=18 on the number of configurations as a function both of N and R, the number of bonds over which overlap is forbidden. Additional Monte Carlo data for large values of N are discussed in relation to the exact enumeration results. Additional properties determined and discussed include mean-square end-to-end distance, ring formation, and order.
Calculations of the Surface Energy for Some Orthorhombic Sulfates
Authors: Walton A. G. , Whitman D. R.
Published: January 2005

The surface energy for the 100 faces of barium, strontium, lead, and calcium sulfates has been calculated for various sizes of very small crystals. These values, when extrapolated to infinite surface area, give for the average surface energy 994, 1110, 1062, and 574 ergs/cm2, respectively.
Pyrolysis of Ethylene Oxide. A Hot Molecule Reaction
Authors: Benson Sidney W.
Published: January 2005

It is proposed that the pyrolysis of ethylene oxide (EO) proceeds via an internal isomerization (similar to that in isoelectronic cyclopropane) to form an excited (CH3CHO)* molecule. It is estimated that the excess energy of this latter is about 85 kcal, which is about 7 kcal in excess of the C–C bond dissociation energy in CH3CHO. The lifetime of (CH3CHO)* for bond fission is estimated to be 10—8.5 sec so that its fate is predominantly quenching at P≥200 mm Hg. Estimates of the isomerization rate give, in good agreement with the inhibited reaction: ki=1014.1510−57/θsec−1where θ=4.575T kcal/mole. Analysis of the chain mechanism indicates a chain length between 1 and 2 with the production of a ``hot'' CH2CHO radical formed by exothermic ring opening of the EO radical. This is probably quenched but may decompose spontaneously to CH2CO+H. Published data on the high temperature reactions (1100°K) give absolute rates in reasonable accord with the 700°K reaction. The lower values of Eact found for the higher temperatures may not be reliable. More meagre data previously published on the pyrolysis of propylene oxide are in good agreement with expectations drawn from the EO system both qualitatively and quantitatively. Other ``hot'' molecule reactions are discussed briefly.
Interactions between Ground-State Nitrogen Atoms and Molecules. The N–N, N–N2, and N2–N2 Interactions
Authors: Vanderslice Joseph T. , Mason Edward A. , Lippincott Ellis R.
Published: January 2005

Potential energy curves for N–N interactions corresponding to the X1Σg+, A3Σu+, 5Σg+, 7Σu+, B3IIg, C3IIu, and a1IIg states of N2 have been calculated, as well as curves for the N–N2 and N2–N2 interactions. All calculations have been based as nearly as possible on experimental data, including spectroscopically determined vibrational energy levels, scattering cross sections of atomic beams in gases, and measured vibrational relaxation times. In cases where experimental data were not available, approximate quantum-mechanical calculations have been made. Results obtained by these various methods are remarkably consistent with one another, and are believed to have good accuracy.
Spectra Emitted from Solid Nitrogen Condensed at Very Low Temperatures from a Gas Discharge
Authors: Peyron M. , Broida H. P.
Published: January 2005

Solid products from electrical discharges containing nitrogen emit visible light at temperatures below 40°K. The observed spectra depend greatly upon (1) the temperature at which the discharge products are condensed, (2) the rate of deposition of the gas, (3) the addition of small amounts of impurities, and (4) the addition of large amounts of inert gases. A detailed survey of the effect of these parameters is presented, in order to understand better the mechanisms responsible for the various types of radiation which are observed.
Relative Rates of Reactions of Oxygen Atoms with Olefins
Authors: Cvetanović R. J.
Published: January 2005

Relative rates of addition of oxygen atoms in their ground electronic state to a number of olefins in the gas phase have been determined at room temperature. These reactions exhibit the following regularities: (1) systematic variation of the rates with the structure of the olefins; (2) specificity with respect to the position of addition of oxygen atoms; and (3) partial molecular rearrangement of the addition products according to definite rules. The observed structural effects and some close analogies with certain olefin addition reactions in solution are discussed in the light of electronic theories of organic chemical reactions. A comparison is made of the absolute values of the rate constants of the reactions of oxygen atoms with olefins, derived from various sources.
Polarization of the Phosphorescence of Naphthalene and Phenanthrene
Authors: Williams Richard
Published: January 2005

Polarization of the phosphorescence of naphthalene and phenanthrene has been observed. The substances were dissolved in EPA glass at 77°K and irradiated with plane polarized exciting light sufficiently monochromatic to be absorbed by only a single electronic transition. The phosphorescence transition is perpendicular to the plane of the ring for phenanthrene and lies in the plane of the ring along the short axis for naphthalene. Comparison of observed polarizations with those predicted for various assignments of the lowest triplet shows that no assignment can be made in the case of phenanthrene. An assignment may be possible in the case of naphthalene though it is subject to uncertainty because of the contribution to the emission intensity which may be due to vibrationally induced transitions.
Knight Shift in Sodium-Ammonia Solutions
Authors: Blumberg W. E. , Das T. P.
Published: January 2005

Two wave functions have been obtained for the electrons in sodium-ammonia solutions by a numerical procedure from two potential wells based on the model proposed by Becker, Lindquist, and Alder for metal-ammonia solutions. These wave functions have been used to calculate the expected Knight shift in the region <0.5 molar by means of an n-electron formalism previously found successful in treating the hyperfine interaction of F centers. The results have been compared with the experimental values of McConnell and Holm for the Knight shifts of Na and N in sodium-ammonia solutions, and agree quite favorably. In particular, these calculations show that the N resonance shift will decrease with dilution, while the Na shift will increase with dilution, between 0.5 and 0.03 molar. The H shift is shown to be less than 10—6 for all concentrations <0.5 molar, giving an explanation why it was not experimentally observed. Dependence of the Knight shift upon concentration is predicted for the range <0.05 molar, which has not yet been covered by experiment.
Polymers and Theory of Numbers. I. The Single-Chain Theory of Degradation
Authors: Nanda V. S. , Pathria R. K.
Published: January 2005

The process of degradation of linear polymers is studied in terms of a corresponding problem in the theory of numbers. On the basis of this analogy, an exact single-chain theory is developed. Expressions for the size distribution among the various fragments and the different averages of the molecular weight are derived. It is shown that the results obtained by earlier authors from probability considerations follow as first approximations from the exact ones obtained here.
Some Notes on the Electron Repelling Property of Alkyl Groups
Authors: Basu Sadhan
Published: January 2005

Electron donation by alkyl groups and bond angle change due to steric requirement have been found to affect the physicochemical properties of simple saturated molecules in exactly similar manner.
Solutions of Metals in Amine Solvents. II. A Conductance Function for Dilute Solutions of Sodium in Liquid Ammonia
Authors: Evers E. Charles , Frank Paul W.
Published: January 2005

A conductance function is derived which represents the experimental data for solutions of sodium in ammonia up to a concentration of approximately 0.04N. The derivation is based on the mass action concept involving species described in models by Becker, Lindquist, and Alder, and by Deigen.
Application of the Monte Carlo Method to the Lattice-Gas Model. I. Two-Dimensional Triangular Lattice
Authors: Salsburg Z. W. , Jacobson J. D. , Fickett W. , Wood W. W.
Published: January 2005

The Monte Carlo numerical method for obtaining statistical mechanical averages in the petite canonical ensemble has been applied to the two-dimensional triangular lattice-gas model. The Monte Carlo procedure described by Rosenbluth et al. and by Wood and Parker has been extended slightly to include the calculation of the partition function. The results are compared with the exact solutions for the two-dimensional lattice and the agreement is well within the fluctuation displayed by the numerical method. The calculations are found to be relatively insensitive to a change in the pseudo-random number sequence and to display no exceptional behavior in the region of the first-order phase transition for small lattices.
Absorption of Acyclic Oxygen Compounds in the Vacuum Ultraviolet. II. Ethers
Authors: Harrison Anna J. , Price Diana R. W.
Published: January 2005

A fluorite prism vacuum spectrograph and a hydrogen lamp have been used to determine the 45 000- to 65 000-cm—1 absorption spectra of dimethyl ether, diethyl ether, divinyl ether, and 1,4-pentadiene in the vapor phase at 22°C.
Short-Range Interaction between a Hydrogen Molecule and a Hydrogen Atom
Authors: Aroeste Henry , Jameson William J.
Published: January 2005

Computations of the interaction at close distances between a hydrogen atom and a hydrogen molecule in their ground states have been made using various modifications of atomic orbital methods for the purpose of decreasing the difference between experimental and theoretical results. A choice of states corresponding to the lower root of the second-order secular equation for such distances appreciably reduces the prior theoretical values. Application of the LCAO method decreases the discrepancy to about 6–8 ev and gives reasonably good qualitative agreement with the experimental values. Although computations for a test case indicate no further improvement when the screening constant is varied, a discussion is presented to clarify the calculation of interaction potentials for this procedure. Results for relaxation in the hydrogen molecule internuclear distance are also given.
Effects of High Pressure on the Near Ultraviolet Vapor Absorption Spectrum of Benzene in a Number of Diluent Gases
Authors: Babb S. E. , Robinson J. M. , Robertson W. W.
Published: January 2005

The absorption spectrum of benzene vapor in a number of gaseous diluents over a wide range of diluent densities has been obtained. The wavelength of absorption shifts to the red in the gases A, H2, N2, CO2, O2, CO, C2H6, and C2H4, to the blue in the diluents He and Ne. Since the light absorber is the same in each case, the relative rates of shift with density should be a function of the physical properties of the diluents. However, no simple correlation has been found to exist between relative shift and such properties of the solvents as polarizability or dielectric constant. Dispersion theory predicts only roughly the relative shifts. No satisfactory explanation has been found for the blue shift obtained in He and Ne.
Dissociation Energies of Some Gaseous Alkali Halide Complex Ions and the Hydrated Ion K(H2O)+
Authors: Chupka William A.
Published: January 2005

A mass spectrometer was used to analyze the ionic species present in the vapors of several alkali halides which were heated in a small oven to temperatures in the range 700–950°K. For the four compounds investigated, NaCl, KCl, KBr, and RbCl, the most abundant ionic species were of the type M+ and M2X+ in comparable amounts. Smaller amounts of M3X2+ ions and, in certain circumstances, negative ions of the type X— and MX2— were also detected. The equilibrium constant was measured as a function of temperature for the reaction M2X(g)+→M(g)++MX(g). Values of the ΔH of this reaction were determined by two independent methods which gave good agreement for all compounds except RbCl. The values of ΔH(0°K) so determined were 42.3, 41.3, and 41.0 kcal/mole for NaCl, KCl, and KBr, respectively. The more reliable value for RbCl was about 40 kcal/mole which agrees well with a theoretically calculated value of about 42 kcal/mole.

An attempt to detect the K(H2O)+ ion in equilibrium with water vapor and KCl at about 840°K was apparently successful, although positive identification of the ion could not be made. The equilibrium constant for the reaction K(H2O)(g)+→K(g)++H2O(g) was measured and gave a value of ΔH(O°K) = 20 kcal/mole.
Vibrational Intensities. XI. CO2 and the Wilson-Wells Method
Authors: Overend John , Youngquist M. J. , Curtis E. C. , Crawford Bryce
Published: January 2005

The Wilson-Wells-Penner-Weber method of determining absorption-band intensities in the infrared has been critically reviewed. This technique has been used to redetermine the intensity of the 670 cm—1 band system of carbon dioxide. The present result, A=241 cm—1/cm atmos at STP agrees well with the curve-of-growth value, A=240 cm—1/cm atmos at STP and demonstrates that, with proper precautions, both methods are capable of producing reliable intensity data.
Reformulation of the Jahn-Teller Theorem
Authors: Clinton William L. , Rice Bernard
Published: January 2005

The Jahn-Teller theorem is reformulated on the basis of the Hellmann-Feynman theorem. Examples are given illustrating the conceptual simplicity of the force approach as opposed to the energetics approach. Methods of calculation are outlined and an estimation of the effect is given for the borane (BH3) molecule.
Gaseous Detonations. XII. Rotational Temperatures of the Hydroxyl Free Radicals
Authors: Kistiakowsky G. B. , Tabbutt F. D.
Published: January 2005

An apparatus is briefly described which permits the photography of the ultraviolet absorption spectrum of the hydroxyl free radicals in gaseous detonation waves with a time resolution of a few microseconds. Using two mixtures, 2H2+O2 and 2H2+O2+0.075 C2H2 at 20 mm pressure, changes were studied in the absorption spectra with the progress of chemical reactions in a detonation wave. Densitometry of the absorption lines in the R2 branch of the O–O band in the 2Σ+→2π transition, combined with the use of the iso-intensity method, showed that the ``rotational temperatures'' of the radicals in their ground electronic state are initially much higher than the ``translational temperatures'' calculated from the experimentally observed and elsehere reported density-time curves in detonation waves of similar gas mixtures. After the completion of the reactions and the attainment of the Chapman-Jouguet state the rotational temperature was found to be slightly lower than the calculated equilibrium temperature, which is attributed to systematic experimental errors. The observed initial lack of equilibration between the translational and rotational temperatures is interpreted to mean that the lifetime of hydroxyl radicals in partially reacted mixtures is comparable to their rotational relaxation time, i.e., is of the order of the time for ten collisions.
Far Infrared Spectrum and the Barrier to Internal Rotation in 1,1,1,2-Tetrafluoroethane
Authors: Danti Alfred , Wood J. L.
Published: January 2005

The spectrum of 1,1,1,2-tetrafluoroethane gas has been examined in the far infrared (50–420 cm—1). Bands were observed at 120, 225, 350, and 409 cm—1. The contour of the strong band at 120 cm—1 is consistent with that to be expected for the torsional oscillation. This frequency would correspond to a triple cosine barrier of 4.2 kcal/mole.
New Method for the Statistical Computation of Polymer Dimensions
Authors: Wall F. T. , Erpenbeck J. J.
Published: January 2005

A new method is described for the generation of excluded volume random walks of contour lengths comparable to those of real polymer molecules. This work was carried out with a high-speed electronic digital computer. An essential feature of the method is an unbiased sample enrichment process used to counteract the attrition resulting from chain intersections. Using the new method, samples were generated for chains of 800 links, a limit imposed by machine storage capacity. In principle the method could be carried even further if more storage were available.

Mean-square end-to-end lengths of the chains are expressed by the equation 〈rn2〉=anb,where n equals the number of links and a and b are constants.
Thermal Conductivity of Water at High Pressures
Authors: Lawson A. W. , Lowell R. , Jain A. L.
Published: January 2005

The thermal conductivity of water has been measured between 30° and 140°C at pressures ranging up to 8000 kg/cm2 using Bridgman's concentric cylinder technique. At atmospheric pressure, the values obtained are about 1% less than the most probable values estimated by Powell. At higher pressures, the values agree well with Bridgman's measurements where the data overlap. The results are discussed in terms of Hall's two fluid model of water.
Optical Activity in Absorbing Media
Authors: Moffitt William , Moscowitz Albert
Published: January 2005

Certain dispersion formulas, relating the ellipticity and molecular rotation of optically active solutions, are derived. These are analogous to the Kramers-Kronig transform relations between the absorption and refractive indices. Some discussion is offered of the factors influencing the respective shapes of absorption and ellipticity curves.
Electron Coupling of Nuclear Spins. II. Molecular Orbital Interpretation of Coupling Constants Observed in Fluorobenzenes
Authors: Williams G. A. , Gutowsky H. S.
Published: January 2005

The H–H, H–F, and F–F coupling constants and relative signs determined previously in high resolution NMR experiments are considered in terms of molecular orbital theory. The data, including the dependence of the coupling upon the relative positions of the atoms in the benzene ring, are sufficient to indicate which of the various interactions contribute most to the coupling. In general, the largest contribution is that carried by s electrons through the Fermi contact interaction. However, there are significant one-electron terms. The H–F and F–F coupling constants suggest that there is about 5% fluorine 2s character in the C–F bond.
Unimolecular Decomposition of Chemically Activated sec-Butyl Radicals from H Atoms plus cis-Butene-2
Authors: Rabinovitch B. S. , Diesen R. W.
Published: January 2005

Chemically activated sec-butyl radicals have been produced at temperatures between —103° and 25°C by reaction of H atoms with cis-butene-2. H atoms were allowed to effuse through a molecular slit into a spherical reactor containing olefine at low pressure. The system resembles the Polanyi diffusion flame, and some solutions for the radial distribution functions of the species involved are given. Disproportionation-recombination ratios for sec-butyl radicals, and for methyl plus butyl radicals, were measured as 0.94 and 0.30 respectively. The ratios of stabilization vs decomposition by C–C rupture for the energized butyl radicals were measured as a function of pressure and temperature. Hydrogen and helium were also used as inert gases. ka the observed rate constant for decomposition is ∼107 sec—1. The energized butyl radicals are closely monoenergetic. The unimolecular decomposition behavior is compared with theory wherein expressions due to Marcus are employed. All vibrational degrees of freedom may be taken as active.
Mobility of Molecules in Liquids near the Glass Temperature
Authors: Bueche F.
Published: January 2005

A theory for the molecular motion in liquids is formulated. It treats the system as a series of molecular shells bound elastically to each other and to a central molecule. The vibrations of this system are analyzed approximately in an effort to find the probability that the central molecule will be left in a hole large enough so it can move to a new position. It is found that the jump frequency of the molecules obeys an equation of the form exp (—E/kT) at high temperatures but conforms to the WLF equation at low temperatures. The anomalous behavior of liquids near the glass temperature is shown to result from the fact that a great deal of cooperation among adjacent molecules must occur if a molecule is to move at low temperatures. The molecular parameters needed to fit the experimental data available are found to be of reasonable magnitude. The influence of various factors such as molecular size, weight and attraction are also discussed. It is concluded that the glass transition is similar in high and low molecular weight substances and is not a property peculiar to macromolecules.
Diffusion in Ethylene Polymers. IV
Authors: McCall David W. , Douglass Dean C. , Anderson Ernest W.
Published: January 2005

Self-diffusion coefficients have been measured for two low molecular weight fractions (M = 4100 and 5800) of a linear polyethylene. The activation energy for the M = 4100 fraction is 5.3 kcal/mole which is near the value 5.6 kcal/mole found for n — C32H66. At 150°C, for this fraction, D = 1.6×10—7 cm2/sec and as 10—7 is near the lower limit of detectability the activation energy is probably not accurately determined. The diffusion coefficient for the M = 5800 fraction is 1.1×10—7 cm2/sec at 150°C. These results, combined with previous results, show that D = κn—5/3, where D is the coefficient of self-diffuison for the normal paraffin CnH2n+2. κ is a constant at a given temperature, 4.5×10—3 cm2/sec at 200°C and 2.5×10—3 cm2/sec at 150°C.
Forbidden Band Systems in Nitrogen. I. The Vegard-Kaplan System in Absorption
Authors: Wilkinson P. G.
Published: January 2005

Two bands belonging to the Vegard-Kaplan system (A3Σu+−X1Σg+) of nitrogen have been found in absorption in paths of 9- 13 meter-atmospheres. These bands at 1689 A (7–0) and 1726 (6–0) are incompletely resolved but show intensity alternation and distribution in agreement with theory. The positions of the band origins and each rotational line agree closely with those calculated from the known molecular constants.

Two other forbidden systems have also been found in absorption. These are the a′1Σu−−X1Σg+ (four bands at 1444 A, 1414 A, 1360 A, and 1331 A) and probably the Δu3−XΣg+1 (one band at 1484 A); they are about three times stronger than the observed Vegard-Kaplan bands The transition probabilities of the known forbidden systems in nitrogen are discussed briefly.
Microwave Spectrum, Molecular Structure of Vinyl Cyanide and a Summary of CC, CH Bond Lengths in Simple Molecules
Authors: Costain C. C. , Stoicheff B. P.
Published: January 2005

The microwave spectra of six isotopic species of vinyl cyanide (acrylonitrile) CH2CHCN have been investigated. From the rotational constants it is shown that the molecule is planar, and has the following structural parameters (exclusive of the CH2 group):

r s ( C ≡ N )=1.163 7   A ,r s ( C − H )=1.086 3   A , r s ( C − C )=1.425 6   A ,∠ C = C − C =122 ∘ 37 ′ , r s ( C = C )=1.338 9   A ,∠ H − C − C =121 ∘ 44 ′ .

The quadrupole hyperfine structure was interpreted according to the asymmetric top treatment leading to a value of eqQ = —4.21±0.04 Mc/sec for the quadrupole coupling constant along the C≡N bond.

A table of the most accurate published values of CC and CH bond lengths is included. A graphical presentation of these results shows that the C–C, C=C, and C–H bond lengths vary linearly with the number of adjacent bonds.
Term Series for a Rotating-Vibrating Diatomic Molecule by Perturbation
Authors: Kilpatrick John E.
Published: January 2005

Expressions for the most important terms for the energy of a rotating-vibrating diatomic molecule as a function of the coefficients of its potential energy, expressed as a power series, have been deduced by perturbation theory. The perturbation polynomials defined in this theory also enable one quickly and easily to calculate to a high order of accuracy the energy levels associated with any one-dimensional oscillator with a smooth, single-minimum potential.
Static Space Charge and Capacitance for Two-Blocking Electrodes
Authors: Macdonald J. Ross
Published: January 2005

A one-dimensional treatment is presented of space-charge effects in materials having two charge-blocking electrodes. Especial attention is given to the situation where univalent, mobile charge carriers of only one sign can recombine bimolecularly with fixed charges of opposite sign; however, the case where noncombining charges of both signs are mobile is also included. Space-charge potential distributions and differential capacitance cannot be obtained explicitly in the general case but have been accurately calculated using a digital computer. Potential vs distance and capacitance curves are presented which illustrate dependence on applied potential, separation of electrodes, and recombination ratio. The results show features often observed experimentally for a wide variety of materials such as photoconductors, semiconductors, and insulators. The treatment is applicable for much higher applied potentials than is the case for the previously considered one blocking electrode situation with charge accumulation at the blocking electrode.
Paramagnetic Resonance of Methyl- and Chloro-Substituted p-Benzosemiquinones
Authors: Venkataraman Balu , Segal Bernice G. , Fraenkel George K.
Published: January 2005

Detailed measurements, made under conditions of high resolution, of the paramagnetic resonance spectra of the negative radical ions of all the methyl- and chloro-substituted p-benzosemiquinones are reported. All the spectra exhibited hyperfine structure which is accounted for in terms of interactions between the unpaired electron and all the protons in the radicals; no chlorine hyperfine splittings were observed. In some of the chlorine compounds anomalous lines, not attributable to the chloro-substituted p-benzosemiquinone ion, appeared; these presumably arise from radicals produced by side reactions. Microwave power saturation was encountered in all the spectra examined. Line widths of all the spectra were observed to depend markedly on the microwave power and on the concentration of the hydroquinone from which the semiquinone was prepared. Separations of the hyperfine components were measured to a high degree of accuracy and splitting constants for individual protons were calculated from the measurements using the method of least squares. Proton splitting constants ranged from a minimum of 1.714 gauss for the methyl group protons in 2,3-dimethyl semiquinone ion to a maximum of 2.595 gauss for the ring protons in that same compound. The variation of the splitting constants with chlorine and methyl group substitutions are shown to obey a nearly additive relation.
Apparent Order of Heterogeneous Spray Reactions
Authors: Williams F. A.
Published: January 2005

It is demonstrated that when measurements are made in a steadily flowing gas in which a spray is suspended, the observed heterogeneous reaction rate order with respect to the material composing the spray is usually determined by the particle size distribution and is largely independent of the single-particle reaction order. An explicit expression for the dependence of the apparent order upon the size distribution is derived.
Dielectric Relaxation in Some Two-Component Systems
Authors: Denney Donald J.
Published: January 2005

Dielectric relaxation measurements were made on a number of two-component systems involving both associated and nonassociated liquids. A single dispersion was found for a mixture containing two alkyl halides. A mixture containing an alkyl halide and an alcohol showed two dispersion regions, the separate complex plane loci being similar in form to the dispersions found for the separate components. The locus of the dispersion in several alkyl halide-hydrocarbon mixtures was not significantly different from that in the pure halides although small deviations of unknown origin were observed at low frequencies. In the 1-propanol-2-methylpentane mixtures studied, the relative amplitudes of the multiple dispersions, characteristic of the alcohol, were little affected down to a concentration of 33 mole percent 1-propanol but had changed drastically at a concentration of 14 mole percent 1-propanol.

The results are discussed in terms of Schallamach's suggestions concerning the molecular nature of these mixtures and the size of the liquid region involved in the dielectric relaxation process.
Relative Intensities of Absorption Bands in Liquid and Gas Phases from Dispersion Theory
Authors: Ferguson E. E.
Published: January 2005

The well-known expression for the ratio of liquid-gas intensities of absorption bands is derived from the point of view of dispersion theory which shows clearly several assumptions implicit in the expression, the most important being the restriction to weak bands. The manner in which liquid and gas oscillator strengths can be determined from liquid dispersion data is discussed and the infrared dispersion data of CS2 is analyzed in this way.
He I Ground-State Wave Function of the Form ψ=f(r1)f(r2)g(r12)*
Authors: Green Louis C. , Stephens Cynthia , Kolchin Eleanor K. , Chen Carolyn Chandler , Rush Patricia P. , Ufford C. W.
Published: January 2005

A variational trial wave function of the form ψ=f(r1)f(r2)g(r12) has been applied to the ground state of He I. In Sec. I, f(r) is taken to be an arbitrary function and g(r12) is taken as linear. The form of f(r) and the slope of g(r12) are chosen to yield the minimum energy. The energy, —5.79613RHehc, and the form of f are compared with the results of earlier work and with the results obtained with analytic functions. A table of f(r) and the charge distribution is given. The charge distribution is compared with that obtained from a Hartree-Fock wave function and the difference is discussed.

In Sec. II, f(r) is taken as an exponential and g(r12) is taken to be an arbitrary function. The coefficient in the exponent in f(r) and the form of g(r12) are chosen to yield the minimum energy. The energy, —5.78252RHehc, and the form of f are compared with the results obtained with analytic wave functions. The behavior of g is shown in a table and by its asymptotic series. The probable effectiveness of ψ if both f(r) and g(r12) are taken as arbi trary is discussed.
Internal Rotation and Infrared Spectra of Formic Acid Monomer and Normal Coordinate Treatment of Out-of-Plane Vibrations of Monomer, Dimer, and Polymer
Authors: Miyazawa Tatsuo , Pitzer Kenneth S.
Published: January 2005

The infrared spectra of the four isotopic species of formic acid were measured in the vapor phase as well as in the solid nitrogen matrix in the region 400–800 cm—1. Absorption bands in the vapor phase were analyzed by considerations of band contours and comparisons with the frequencies distinctly observed in the matrix, and the previous assignment was revised. The torsional vibrations of the terminal OH groups of short chain polymers of HCOOH were observed in the matrix at 685 and 694 cm—1. The OH torsional frequencies of the trans isomer were located in the vapor phase at 582 (HCOOH), 576 (DCOOH), 450 (HCOOD), and 448 cm—1 (DCOOD). The energy difference between the two isomers was determined to be 2.0±0.3 kcal/mole. The potential hindering internal rotation was calculated to be 2V (kcal/mole)=2·1(1−cosθ)+9·9(1−cos2θ)−0·1(1−cos3θ) from the energy difference and the fundamental torsional frequencies. The entropy of mixing of the two isomers was found to be 0.3±0.1 cal deg—1 mole—1 at 25°C. A normal coordinate treatment was made of the cis and trans isomers of monomer and of the dimer and polymer. The double bond characters calculated from the torsional potential constant agree with those calculated from bond lengths.
Neighbor Interactions and Internal Rotations in Polymer Molecules. III. Statistics of Interdependent Rotations and Their Application to the Polyethylene Molecule
Authors: Lifson Shneior
Published: January 2005

The internal rotations around the skeletal bonds of polyethylene are hindered due to interaction between the neighboring hydrogens. Since second and higher orders of neighborhood are not negligible, the internal rotations are interdependent. The statistics of such interdependent rotations is developed and applied to obtain the configurational partition function and the mean-square end-to-end distance of the macromolecule.
C13 and Deuterium Isotope Effects in the Photolysis of Methyl and Ethyl Bromide
Authors: Gordus Adon A. , Bernstein Richard B.
Published: January 2005

Relative rates of formation of isotopic radicals in the photolysis of gaseous methyl and ethyl bromide have been measured. Photolyses (2537 A) were carried out in a large excess of cyclopentane. Methyl (or ethyl) radicals formed in the primary C–Br bond scission abstract H from cyclopentane to form methane (or ethane). For methyl bromide, the C12/C13 enrichment factor for the first fraction of the methane was 1.039±0.003. The corresponding factor for the α-carbon—Br rupture in ethyl bromide was 1.041±0.004. In the deuterium experiments, CH3Br—CD3Br mixtures in excess cyclopentane were photolyzed. The H/D fractionation factor (based on CH4/CD3H) was 1.41±0.01.

The difference in rates of formation of isotopic radicals is due to the difference in ultraviolet absorption coefficients of the isotopic alkyl bromides. At 2537 A the observed ratio of the extinction coefficient of CH3Br relative to that of CD3Br is 1.38±0.05.
Mutual Diffusion of Pairs of Rare Gases at Different Temperatures
Authors: Srivastava B. N. , Srivastava K. P.
Published: January 2005

The coefficient of mutual diffusion of the binary gas mixtures Ne—A, A—Kr, and Ne–Kr has been determined at 0°, 15°, 30°, and 45°C. Diffusion is allowed to take place between two diffusion bulbs through a precision capillary tube and samples of gas are withdrawn from one bulb at different times and analyzed by a differential conductivity analyzer. From the experimentally determined values of the diffusion coefficient at different temperatures the unlike interaction parameters for the above gas pairs have been calculated by two different methods on the Lennard-Jones 12:6 model. These values of the force parameters are found to be in good agreement with those obtained from the usual combination rules and also from the thermal diffusion data following the method of Srivastava and Madan. These values are found to reproduce the experimental data on mutual diffusion quite satisfactorily.

With Kelvin's method, these data have also been utilized to calculate the self-diffusion coefficient of neon, argon, and krypton.
Acceptor Properties, Reorganization Energies, and π Bonding in the Boron and Aluminum Halides
Authors: Cotton F. Albert , Leto Joseph R.
Published: January 2005

Simple MO theory has been used to estimate the strength of π bonding in the planar, monomeric boron and aluminum halide molecules by partitioning the total energy of dissociation to valence state atoms according to relative values of σ and π overlaps. These π-bond energies have been used to determine the energies required to reorganize the planar molecules to the pyramidal forms existing in their adducts with Lewis bases and the effects of these reorganization energies on the relative over-all acceptor strengths of the halides is discussed. A number of independent checks indicate that the calculated energies are reasonable.
Characterization of Polymer Structures on Helical Point Nets
Authors: Hughes R. E. , Lauer James L.
Published: January 2005

The extension of a polymer chain through many contiguous unit cells in a crystallite requires a discrete relationship between the crystallographic translation identity period and the structural identity period within the chain. This relationship can be uniquely expressed by describing the chain structure in terms of a helical point net.

Helical point nets can be defined in terms of standard screw axis nomenclature, using the translation-rotation operators pq. Integral values of the p's and q's produce all possible nets and their enantiomorphs. The net points thus defined have the property of identity through the operators pq.

The chain structures of polymers in the crystalline state can thus be defined simply in terms of the structure about one net point. Introduction of the restrictions of bond distances and angles limits the number of possible nets for a given translation identity period. One-atom and two-atom structures are considered in detail, and the extension to multiatom structures is indicated.
Perturbation Calculations in Equilibrium Statistical Mechanics. I. Hard Sphere Basis Potential
Authors: Smith E. B. , Alder B. J.
Published: January 2005

A study is made of the effect of potential perturbations on the equilibrium properties of a hard sphere system at both high and low densities. The perturbation is evaluated beyond the first-order term for the second and third virial coefficients to estimate the region of convergence. The results of the first-order perturbation from the virial expansion, superposition theory, and free-volume theory are compared. A comparison with experimental data is made to show the applicability of this perturbation from a hard sphere potential to the estimation of the equilibrium properties of a great variety of gases at moderately high temperatures.
Thermal Conductivity and Eucken Correction for Diatomic Gases and Binary Gas Mixtures
Authors: Srivastava B. N. , Srivastava R. C.
Published: January 2005

The thermal conductivity of pure oxygen, nitrogen, and hydrogen gases and of the binary gas mixtures O2—A, N2—A, and H2—A at several concentrations have been measured by using a thick-wire conductivity cell at 38°C. These data have been used to calculate the Eucken factor for the diatomic gases and the binary gas mixtures. The experimental value of the thermal conductivity and the Eucken factor have been compared with the theoretical values obtained on the Lennard-Jones (12:6) model. Hirschfelder's recent expression for the thermal conductivity of polyatomic gas mixtures has also been tested at some length. It is found that Hirschfelder's expression is substantially correct in its dependence on the individual conductivities.
Infrared Spectra of Alkoxyboranes. I. Dimethoxyborane and Dimethoxyborane-d
Authors: Lehmann Walter J. , Onak Thomas P. , Shapiro I.
Published: January 2005

Frequency assignments are made, based on the infrared spectra of gaseous HB (OCH3)2 and DB (OCH3)2. A band previously reported in the literature for trimethoxyborane is attributed to an impurity.
Infrared Spectra of Alkoxyboranes. III. Di- and Triethoxyboranes
Authors: Lehmann W. J. , Weiss H. G. , Shapiro I.
Published: January 2005

Frequency assignments are made for the infrared spectra of gaseous triethoxyborane, diethoxyborane, and diethoxyborane-d. A new experimental technique was applied in an effort to detect transitory intermediates in the alcoholysis of diborane; no monoethoxyborane was detected. When alcohol was added to diborane, triethoxyborane appeared only after all diborane had been converted to diethoxyborane. Transfer of ethoxy groups between boron atoms is slow, while hydrogen exchange is rapid.
United Atom Treatment of the Behavior of Potential Energy Curves of Diatomic Molecules for Small R
Authors: Bingel Werner A.
Published: January 2005

It is shown that the potential energy function V (R) of any state of a diatomic molecule can be expanded for small internuclear distances, in the from V(R)=[(ZaZb)/R]+Wu+E2·R2+E3·R3+···, where Wu is the energy of that state of the united atom to which the molecular state under consideration connects. Explicit expressions for the coefficients E2, E3 are given in terms of the electronic charge density of the united atom. Applications of the derived energy expansion are discussed.
Nuclear Quadrupole Coupling in the Alkali Chloroiodides. II. Iodine Resonances
Authors: Yamasaki R. S. , Cornwell C. D.
Published: January 2005

Frequencies are reported for m=±12↔±32 transitions of I127 nuclei in polycrystalline samples at 25°C of CsICl2, RbICl2, KICl2, KICl2·H2O, CsICl4, RbICl4, KICl4, KICl4·H2O, NaICl4·2H2O. The coaxial cavity super-regenerative oscillator (250–610 Mc/sec) used for these measurements is described. The average quadrupole coupling constants are —3110 Mc/sec for ICl2— and +3090 Mc/sec for ICl4—. These values are shown to be entirely consistent with resonance hybrid structures which had been selected previously for the discussion of the chlorine resonance data.

The coupling constants are used to estimate electron populations for valence orbitals of I and Cl, and, with certain assumptions, to find approximate MO's of LCAO form for the bonding electrons. The conclusion reached is that the attainment by iodine of higher valences in these ions is due more to transfer of charge to chlorine atoms than to promotion to higher orbitals of iodine. It appears that most of the covalent binding present arises from an MO in which an iodine p orbital is associated with a symmetry orbital made up of collinear sp hybrid orbitals of two attached chlorine atoms.
Dielectric Loss in 66 Nylon (Polyhexamethylene Adipamide)
Authors: Boyd Richard H.
Published: January 2005

The dielectric loss in 66 nylon (polyhexamethylene adipamide) has been studied over a range of temperatures (—40 to 100°C) and frequencies (50 cps—70 Mc). The effects of radiation induced crosslinking and hydrogen bonding solutes were studied.

The principal dipole orientation absorption is similar to that in amorphous polar polymers in that it involves long chain segment rearrangements in the amorphous regions. However no temperature range was found in which the distribution of relaxation times is independent of temperature, thus there is no time-temperature superposition. The effect of crosslinking allows a semiquantitative estimate of the segment length of about 15 amide groups to be made. The plasticizing effect of the solutes and their effect on the activation energy for dielectric absorption and the relaxation time distribution is discussed. The static dielectric constant associated with the long chain segment rearrangement mechanism is derived. From its temperature and solute dependence, the equilibrium disappearance of this mechanism at low temperatures is inferred. This disappearance seems to be associated with increased interchain coupling. The solute dependence also shows the presence of tightly bound solute molecules at the amide groups.

A weak absorption occurring at lower temperatures (—10°C and 100 cps) is also observed.

Comparison of the dielectric absorption with mechanical absorption is made.