bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Kinetics of the Disorder-Order Transformation in Cu3Au
Authors: Lord Norman W.
Published: January 2005

The isothermal order-dependent change in the Young's modulus of a single crystal of Cu3Au is measured as a function of time at various temperatures in the range 279.3°C to 384.3°C. These temperatures were reached by quenching rapidly from an equilibrium state 28.2°C above the critical temperature (386.0°C).

The time variations of Young's modulus indicate two distinct stages of the disorder-order transformation. The initial stage starts immediately and is completed a few minutes after quenching, while the later stage requires a few minutes before starting and then proceeds very slowly toward an equilibrium state. ``Relative relaxation times'' are associated with each of them.

In conformance with the work of Sykes and Evans and others, the initial stage is described as the formation of contiguous, antiphase, ordered domains by means of normal atomic interdiffusion. The later stage consists of the coalescence of these domains and requires at least two different geometrically constrained diffusion processes.
A Theoretical Model of a Gaseous Combustion Wave Governed by a First-Order Reaction
Authors: Friedman Raymond , Burke Edward
Published: January 2005

Numerical solutions are obtained for differential equations describing a hypothetical model of a laminar flame. A first-order irreversible reaction with approximately exponential dependence of rate upon temperature is assumed, with interdiffusion of reactant and product molecules. The temperature dependence of thermal conductivity, diffusion coefficient, and gas density is taken into account. When the equations are in suitable form, the dimensionless burning velocity is an eigenvalue whose magnitude depends on two dimensionless parameters; ε (the ratio of activation energy to burned gas temperature) and α (the ratio of heat flow to diffusional flow). An I.B.M. Card-Programmed Electronic Calculator was used to obtain solutions accurate to two percent, for a wide range of values of ε and α. Interdiffusion is found to reduce the burning velocity, the effect being more pronounced when ε is large. The results for α equal to unity are compared with the approximate burning-velocity equation of Zeldovich and Frank-Kamenetsky, and the latter is shown to be valid only when ε is large.
Kinetics of Two Exchange Reactions Involving Diborane
Authors: Maybury P. Calvin , Koski W. S.
Published: January 2005

The kinetics of the exchange between deuterium and diborane were studied over a temperature range of 25°—75°C, and it was found that the reaction was 32 order with respect to diborane and zero order with respect to deuterium at high pressures. At low pressures the zero-order dependence of the deuterium changed to first-order. The activation energy of the zero-order reaction was 20.4±2 kcal/mole. A mechanism is proposed in which the borine radical reacts with deuterium on the wall and is followed by a rate determining bimolecular collision between the partially deuterated borine radical and a diborane molecule.

The closely related exchange reaction between normal and completely deuterated diborane was also investigated. The total order of this reaction was 32, and it had an activation energy of 21.8±3 kcal/mole. A mechanism is proposed which involves the collision between a borine radical and a diborane molecule as the rate determining step.
The Limiting Thickness of an Electrolyzed Gas Film Capable of Sustaining a Given Negative Pressure
Authors: Briggs Lyman J.
Published: January 2005

The critical thickness of a gas film that is just capable of withstanding a given negative pressure PN in a liquid column has been studied. The film was generated electrolytically on the surface of a spherical platinum electrode of known area. The number of gas molecules corresponding to the measured charge required to release the negative column was then computed from the relation between the Faraday constant and Avogadro's number. The number of gas molecules required to form a monolayer on the electrode was next computed from the molecular diameter, based on van der Waals' equation. The ratio of these numbers gives the ``thickness'' t of the film in fractions of a monolayer.

Both O2 and H2 gas films were measured under conditions such that the same number of gas molecules were deposited on the same electrode and the corresponding critical negative pressures observed. Assuming the effectiveness of the film to be proportional to the area covered, the ratio of the diameters of the O2 and H2 molecules is inversely proportional to the square root of the ratio of their critical negative pressures. This gave O2/H2=1.11 as compared with 1.06 from measurements based on van der Waals' equation.

Measurements of oxygen films were made at various negative pressures, ranging from PN=90 cm of water, t=0.55 monolayer, to PN=4 cm, t=0.87 monolayer. The results lie on a smooth curve down to PN=10 cm, t increasing steadily as PN is reduced. Below PN=10 cm, the thickness of the film no longer increases, indicating that the zone of influence of the gas molecule extends beyond its projected area.
On the Emission Bands of the NO Molecule in the Vacuum Ultraviolet Region
Authors: Tanaka Yoshio
Published: January 2005

With 85-cm and 21-foot normal-incidence vacuum spectrographs the NO emission spectrum in the far-ultraviolet region was investigated. The existence of the ε-system is confirmed. The β′ bands are reinvestigated, and a curious appearance was observed in the (4,0) band. New bands which have an appearance similar to the β′ bands are observed in the region of 1500A, and tentative analysis is made.
Rotational Isomerism in Chloroacetone
Authors: Mizushima San-ichiro , Shimanouchi Takehiko , Miyazawa Tatsuo , Ichishima Isao , Kuratani Kenji , Nakagawa Ichiro , Shido Nobuhiko
Published: January 2005

Raman spectra of chloroacetone were measured in the liquid and solid states and in solutions. Infrared absorption spectra of this substance were measured in the gaseous, liquid, and solid states and in solutions. The temperature dependence of the intensity of the Raman lines and of the absorption bands were measured in the liquid state. From the experimental results together with the dipole data it was concluded that chloroacetone exists in two molecular forms in the liquid and gaseous states and in one form in the solid state. The less stable form in the liquid state becomes much more abundant than the other form in the gaseous state. Some considerations on the nature of hindering potential of internal rotation have been made.
Rotation-Vibration Spectra of Diatomic and Simple Polyatomic Molecules with Long Absorbing Paths. X. The Spectrum of Tri-Deuteromethane in the Photographic Infrared
Authors: Bovey L. F. H.
Published: January 2005

The absorption spectrum of CD3H has been investigated under high resolution in the photographic infrared with absorbing paths of up to 7 m atmos obtained by multiple reflection. Two simple parallel bands were observed at 8870A and 11590A. The K structure in the former was clearly resolved. The rotational structure of the two bands was analyzed yielding B0=3.2787±0.0010 cm−1.On the assumption of tetrahedral symmetry for the CD3H molecule this value leads to a C–H distance r0=(1.09193±0.00017)×10−8 cm.This value is compared with the corresponding values obtained by other authors from studies of CH4 and CH3D.
A Theory of Sensitized Luminescence in Solids
Authors: Dexter D. L.
Published: January 2005

The term ``sensitized luminescence'' in crystalline phosphors refers to the phenomenon whereby an impurity (activator, or emitter) is enabled to luminesce upon the absorption of light in a different type of center (sensitizer, or absorber) and upon the subsequent radiationless transfer of energy from the sensitizer to the activator. The resonance theory of Förster, which involves only allowed transitions, is extended to include transfer by means of forbidden transitions which, it is concluded, are responsible for the transfer in all inorganic systems yet investigated. The transfer mechanisms of importance are, in order of decreasing strength, the overlapping of the electric dipole fields of the sensitizer and the activator, the overlapping of the dipole field of the sensitizer with the quadrupole field of the activator, and exchange effects. These mechanisms will give rise to ``sensitization'' of about 103−104, 102, and 30 lattice sites surrounding each sensitizer in typical systems. The dependence of transfer efficiency upon sensitizer and activator concentrations and on temperature are discussed. Application is made of the theory to experimental results on inorganic phosphors, and further experiments are suggested.
The Molecular Structure, Dipole Moment, and g Factor of Ozone from Its Microwave Spectrum
Authors: Trambarulo R. , Ghosh S. N. , Burrus C. A. , Gordy W.
Published: January 2005

Four low-J rotational transitions of 0316 have been measured in the region from 42 to 118 kmc. The rotational spectroscopic constants found are A = 106,530.0±1.1 Mc, B = 13,349.06±0.06 Mc, C = 11,834.3±1.1 Mc. The oxygen nuclei form an isosceles triangle with an apex angle of 116°49′±30′, and the two equal internuclear distances are 1.278±0.003A. From the Stark splitting of the 20,2→11,1 transition the dipole moment is 0.53±0.02 debye. Zeeman splittings of this transition show that ozone is not significantly paramagnetic.
The Magnetic Properties of Some Anhydrous Chlorides
Authors: Elliott Norman
Published: January 2005

The magnetic susceptibility of CoCl2 and of solid solutions of CoCl2 with ZnCl2 and CdCl2 have been measured over the temperature range 76°—296°K. The susceptibility of CoCl2 is very little affected by dilution with isomorphous chlorides. The results are interpreted as showing that CoCl2 deviates from Curie's law in its behavior because of a crystalline field Stark effect rather than Heisenberg spin-spin exchange.
Application of the Fermi-Thomas Model in Computing the Dipole Moment of Iodine Chloride
Authors: Glazer Herbert , Reiss Howard
Published: January 2005

The Fermi-Thomas statistical method is applied to the molecule ICl and the nonlinear boundary value problem solved by means of the relaxation method of Southwell. In this manner it is possible to construct an electron density map for ICl and to compute its diploe moment. The computed moment compares favorably in magnitude with the measured and has the correct sense.

It appears as though the statistical method will be useful in estimating the senses of dipole moments when they are not clearly evident from experiment.
Manometric Determination of the Density of Liquid Ozone
Authors: Brown Callaway , Franson Karl D.
Published: January 2005

A manometric method for density of liquids at low temperatures is described and applied to liquid ozone. Results in g cm−3: 1.571 at −183°C, 1.595 at −188°C, and 1.614 at −195°C with an average deviation from the mean of ±0.003. A simple method of test for magnetic susceptibility of low temperature liquid is described and used to detect residual oxygen in liquid ozone. Vacuum distilled liquid ozone is shown to contain less than 0.1 percent oxygen.
The Photochlorination of Methyl Chloroformate in the Gas Phase
Authors: Brandy J. H. , Le Roy D. J.
Published: January 2005

Under similar conditions of concentration and light absorption the rate of the gas phase reaction is almost the same as the rate in carbon tetrachloride solution, studied previously, although the mechanism is somewhat different. The gas-phase reaction is not inhibited by products and the bimolecular chain termination step consists in the formation of chlorine, rather than monochloromethyl chloroformate. First-order removal of chlorine atoms becomes important at low light intensities.

The ratio of the rate constant for hydrogen chloride formation to that for first-order chain termination is the same in the gas phase as in carbon tetrachloride solution within the accuracy of the measurements.
Infrared and Raman Spectra of Fluorinated Ethanes. VII. CCl3CF2Cl and CCl3CFCl2
Authors: Nielsen J. Rud , Liang C. Y. , Smith D. C. , Alpert Morris
Published: January 2005

The infrared spectra of liquid CCl3CF2Cl and of CCl3CFCl2 as glass and in CS2 solution, have been obtained in the region from 2 to 38μ with the aid of LiF, NaCl, KBr, and KRS−5 prisms. The Raman spectra of these compounds in the liquid state, at about 50° and 120°C, respectively, were photographed with a three-prism glass spectrograph of linear dispersion 15A/mm at 4358A. Relative intensities and depolarization ratios were measured for all but the weakest Raman bands. Complete assignments of fundamental vibration frequencies have been made, the spectra have been interpreted in detail, and thermodynamic functions have been calculated.
A Statistical Theory of Order-Disorder Equilibrium at High Temperatures
Authors: Schwed Philip , Groetzinger Gerhart
Published: January 2005

An expression for the free energy of a binary cubic alloy undergoing the order-disorder transition is derived by direct evaluation of the configurational partition function.
The Intermolecular Force Constants of Fluorine
Authors: White David , Hu Jih-Heng , Johnston Herrick L.
Published: January 2005

The intermolecular force constants of gaseous fluorine have been determined from measurements of the second virial coefficients in the region 80–300°K. On the assumption that gas imperfection results only from binary collisions of spherical nonpolar molecules whose potential is of the form given by Eq. (1), the force constants obtained were r0=3.61±0.04A and ε0/k=121±3°K. These force constants yield viscosities in good agreement with the experimental data of Kanda if the high temperature point is discarded.
Effects of Self-Absorption on Rotational ``Temperatures'' of OH in Flames
Authors: Broida Herbert P.
Published: January 2005

Penner's method of calculating effects of absorption on measured OH (2Σ+) rotational distributions has been applied to the R2 branch and the results compared with intensity measurements of acetylene-oxygen flames at atmospheric pressure. It is shown that distributions in the hot gases above the reaction zone are in agreement with calculated distributions and that for isothermal regions the method can give both emissivity and rotational ``temperature,'' even when there is appreciable self-absorption. Measured intensities in the reaction zone indicate that there is a rotational ``temperature'' several hundred degrees in excess of the adiabatic temperature and that the ``temperature'' of the emitters is greater than that of the absorbers.
Investigation of the Surface Reaction of Oxygen with Carbon on Tungsten with the Field Emission Microscope
Authors: Klein Ralph
Published: January 2005

The adsorption of oxygen and carbon on tungsten and the surface reaction between carbon and oxygen on tungsten have been studied by means of the field emission microscope. Emission patterns for oxygen on tungsten, carbon on tungsten, and oxygen and carbon together on tungsten under a variety of temperature pretreatment conditions have been obtained. Average work functions over all exposed crystallographic planes, calculated from measured voltages and emission currents on the basis of the Fowler-Nordheim equation, give a measure of surface coverage in the case of oxygen on tungsten. The similarity of the emission-pattern changes in the evaporation of oxygen from tungsten with those found in the reaction between carbon and oxygen on tungsten suggests that the rate-controlling step in the reaction is desorption of oxygen from the tungsten surface. Diffusion of carbon into the tungsten lattice plays no role in the pattern changes since, in the absence of oxygen, the carbon-on-tungsten surface is found to be very stable.
Molecular Size Distribution in the Copolymerization of N-Carboxyamino Acid Anhydrides
Authors: Gold Louis
Published: January 2005

The theory of molecular size distributions which are intrinsically Poisson in character is extended to cover two complementary aspects of copolymerization which are specifically adapted to polypeptide synthesis via the N-carboxyamino acid anhydride (Leuchs monomer). The statistical aspects for (1) discrete monomer reacting with a Poisson ensemble of initiators and (2) the circumstance of an array of monomers copolymerized by a discrete initiator are delineated. Explicit relations for the number and weight average molecular weights are derived.
The Polarizability and Configuration of n-Paraffins
Authors: Stein Richard S.
Published: January 2005

The principal polarizabilities of a flexible paraffin hydrocarbon molecule may be calculated from the bond polarizabilities. The result will depend upon the average configuration of the molecule. The light scattering depolarization which is calculated from these polarizabilities may be compared with measured values. The comparison favors a configuration requiring preferential trans-arrangements about carbon-carbon single bonds.
Chemical Effects Due to the Ionization of Impurities in Semiconductors
Authors: Reiss Howard
Published: January 2005

This paper contains a theoretical account of the possible effects which the ionization of donor and acceptor impurities can induce in the thermodynamic phase relations involving their solutions with semiconductors. These effects reflect the energy band structure of the semiconductor. Furthermore, the phenomenon has an interest of its own, for within a certain range of experimental conditions the effects can be attributed to a chemical-like, mass action behavior of the electrons which play the roles of negative ions.

Section V is a brief discussion of a fine point concerning the Fermi level. It is shown that although the Fermi level is certainly the electronic electrochemical potential, it is not the Gibbs free energy per electron unless the density of electron energy levels is linear in the volume of the system.
An Aid in the Determination of Internal Parameters from Rotational Constants for Polyatomic Molecules
Authors: Kivelson Daniel , Wilson E. Bright
Published: January 2005

The rules given in a previous paper for the derivatives of the principal moments of inertia with respect to internal parameters are shown to be applicable to the problem of obtaining molecular parameters from spectroscopic moments of inertia, even though the conditions on the coordinate axes are different in the two cases.
Bromination of Hydrocarbons. VI. Photochemical and Thermal Bromination of Toluene. Bond Dissociation Energies
Authors: Anderson Herbert R. , Scheraga Harold A. , VanArtsdalen Ervin R.
Published: January 2005

With the aid of a high temperature, high vacuum, corrosion-resistant valve and photometers operating with high sensitivity at low light intensities, it has been possible to study the homogeneous gas-phase kinetics of the photochemical and thermal bromination of toluene. Infrared analyses indicated that the reaction is predominantly a side-chain substitution, the products being benzyl bromide and hydrogen bromide. The photochemical reaction, studied in the temperature range 82° to 132°C, was strongly inhibited by hydrogen bromide. The thermal reaction was studied in the absence of added hydrogen bromide at 166°C. Except for the step involving the dissociation of bromine molecules, both the photochemical and thermal mechanisms involve the same type of atom and radical chain, as found previously for the bromination of simple alkanes. The corrected activation energy of the over-all reaction, as determined from the temperature coefficient of the photochemical reaction, was found to be 7.2 kcal/mole. This value was assigned to the rate determining step Br+RH=R+HBr. From the temperature dependence of the hydrogen bromide inhibition, the activation energy for the reverse of this step was assigned the value 5.0 kcal/mole permitting the C–H bond dissociation energy in the alkyl side chain of toluene to be estimated as 89.5 kcal/mole at room temperature. The discrepancy between this value and Szwarc's value of 77.5 kcal/mole from pyrolysis studies has been pointed out. The efficiency of toluene as a third body in the homogeneous recombination of bromine atoms, and also problems relating to steric effects in atom and radical reactions have been discussed.
Effect of Isotopic Substitution on the Entropy, Enthalpy, and Heat Capacity of Ideal Gases. I. Systems in Thermal Equilibrium. II. Chemically Reacting Systems
Authors: Bigeleisen Jacob
Published: January 2005

The formulas of Bigeleisen and Mayer for the free energy difference between isotopic compounds are used to derive formulas for the similar differences in entropy, enthalpy, and heat capacity. Tables of these functions are calculated. The analogous quantities in the ``thermodynamics of reaction rates'' are discussed. Several useful formulas for the entropy differences of isotopic molecules are derived.
Intermolecular Potentials from Dielectric Polarization in Polar Gases
Authors: Harris Frank E. , Alder Berni J.
Published: January 2005

A theory which relates the dielectric polarization of polar gases to the intermolecular potential is formulated. In it occurs an expansion in powers of 1/V, analogous to the virial expansion. The convergence of this series is briefly discussed, and the impossibility of rotational transitions in the gas phase is shown. Evaluation is limited to the leading term of the expansion, which involves interactions of a pair of molecules only and which is calculable from a knowledge of the intermolecular potential. Various intermolecular potentials consistent with virial data are introduced, and the results are compared with experiment for ammonia, methyl fluoride, and hydrogen fluoride. In view of the unsatisfactory precision of the experimental data, the agreement is as good as can be expected and is qualitatively in agreement with previous concepts of the strength and nature of the hydrogen bond.
Diffusion in Liquid Sulfur
Authors: Saxton R. L. , Drickamer H. G.
Published: January 2005

Diffusion coefficients have been measured in liquid sulfur over the range 120°C—320°C. Two varieties of sulfur, both treated to remove organic impurities, were used. No essential difference was found between them. The break in the diffusion rate occurs at a lower temperature than does the break in the viscosity curve, and the total drop in diffusion rate is much smaller than the rise in viscosity. The effect of added impurity is also less important for diffusion than for flow. This is attributed to the smaller effective moving segment in molecular motion.
Phase Equilibrium in the System Calcite-Aragonite
Authors: Jamieson John C.
Published: January 2005

The equilibrium curve for two of the phases of CaCO3, calcite-aragonite, has been determined as a function of temperature and pressure over the range 25–80°C and several thousand kg/cm2, using the electrical conductivity of aqueous solutions of each form. Aragonite is proved to be the high pressure modification. From the determined equilibrium curve, various thermodynamic quantities are obtained in a more accurate fashion than previously possible. All normal natural occurrences of aragonite must be due to metastable formation rather than equilibrium, since the geothermal gradient lies completely in the calcite field.
Vibrational Spectra of Fluorinated Aromatics. V. 1,3-Difluorobenzene
Authors: Ferguson E. E. , Collins R. L. , Nielsen J. Rud , Smith D. C.
Published: January 2005

The infrared absorption spectrum of liquid 1,3-difluorobenzene has been obtained in the region 2–22μ with the aid of LiF, NaCl, and KBr prisms. The contours of the strong infrared bands of the gaseous phase have also been observed in the region 5–22μ. The Raman spectrum of the liquid has been photographed with a three-prism glass spectrograph of linear dispersion 15 A/mm at 4358A, and depolarization ratios have been measured for the stronger Raman bands. A complete assignment of fundamental vibration frequencies is given and the spectra are interpreted in detail.
Hot Atom Chemistry of the Alkyl Bromides; Absence of Effects Due to High Radiation Density; Isotope Separation in Solids
Authors: Rowland Frank S. , Libby W. F.
Published: January 2005

A 30-curie polonium-beryllium neutron source which gives less than 0.1 roentgen per hour in close contact was used to study the hot atom chemistry of a selection of alkyl bromides. Comparison of the results with those obtained with ordinary neutron sources containing gamma rays in abundance up to 700 roentgen/hour equivalent strongly indicates that the essential phenomena reported are free of effects due to the gamma-radiation density.

The separation of the bromine isotopes in crystalline alkyl bromides has been observed in several additional cases. No isotope effect is shown with CBr4, however, nor with frozen glasses. The possible theoretical significance of these results is discussed.
Effects of Electronic Charge Transfer between Adsorbate and Solid on Chemisorption and Catalysis
Authors: Weisz P. B.
Published: January 2005

When chemisorption on a semiconductive solid is accompanied by electronic charge transfer between adsorbate and solid, an electronic boundary layer analogous to that in rectifying junctions may develop and polarization of charges in the solid may result. These phenomena may limit or control the chemisorption characteristics. The boundary layer theory developed for electrical contacts and elementary considerations concerning the effect of the polarization potential are applied to derive the form of relationships for the extent, heats, and rates of chemisorption and some consequences with respect to catalysis. An attempt is made to illustrate the detailed physical processes in order to examine the meaning of ``heterogeneity'' and ``active centers'' in cases of this type of chemisorption.
Studies of Bond Rupture in the Decay of RaD as Tetramethyl Lead
Authors: Edwards R. R. , Day J. M. , Overman R. F.
Published: January 2005

Studies of bond rupture in tetramethyl lead caused by the beta decay of Pb210(RaD) have been made in solution and in vapor phase. The apparent bond rupture did not show the simple concentration dependence predicted for condensed systems by the cage hypothesis. Vapor phase results were consistent with those from solution in indicating failure of bond rupture in the primary beta and internal conversion processes. Indications are that bond rupture results from secondary processes involving neighboring atoms following the decay process.
Free-Electron Network Model for Conjugated Systems. II. Numerical Calculations
Authors: Scherr Charles W.
Published: January 2005

Numerical calculations are carried out on a large number of aromatic and polyene type conjugated molecules by the methods of the first paper of this series. These calculations include all energy levels, the wavelengths of the first four electronic transitions, the complete π-electron wave functions, the bond densities and bond orders, free valence and reactivities, and dipole moments. A method of estimation of bond lengths with a root-mean-square error of 0.016A is presented. Wherever possible, comparisons are made with experiment and with the results of the LCAO molecular orbital theory in the approximation developed by Coulson and Longuet-Higgins. The results in general are at least as good as those of the LCAO calculations.
Infrared Spectra of Gaseous and Crystalline Cyanogen Halides
Authors: Freitag Walter O. , Nixon Eugene R.
Published: January 2005

The infrared spectra of gaseous ClCN and BrCN at room temperature are reported for the LiF, NaCl, KBr, and CsBr prism regions. Several upper stage bands as well as bands due to C13 appear in both spectra. Assignments are given, from which a number of the vibrational constants are evaluated and the Fermi resonant levels treated by a first-order perturbation method.

The spectra of crystalline ClCN, BrCN, and ICN at −180°C is also recorded. Absorption bands, including several due to C13 and N15, are assigned and the spectra are discussed in terms of the available x-ray crystal data.
Adsorption of He3 and He4 on Activated Charcoal
Authors: Hoffman C. J. , Edeskuty F. J. , Hammel E. F.
Published: January 2005

The adsorption on activated charcoal of pure He3 at 2.5 and 3°K, and of pure He4 at 4°K has been measured. The volume of gas necessary to form a monolayer is approximately the same for the two isotopes. It is shown that capillary condensation does not occur in this adsorbent at low saturations. The data have been analyzed by a number of methods with consistent results.
Selection Rules for a Freely Rotating Ethane—Type Molecule
Authors: Bauman Robert P.
Published: January 2005

Recent investigations of dimethyl acetylene and perfluorodimethyl acetylene have suggested that the selection rules for a freely rotating ethane-type molecule should be those of the point group D3d rather than D3h. A demonstration that this holds under the usual Born-Oppenheimer approximation is given. Possible deviations from this in any particular case should depend upon the characteristics of the individual molecule.
Ground State of the Helium-Hydride Ion
Authors: Evett Arthur A.
Published: January 2005

The variational method developed by James and Coolidge was applied to the ground state of (He H)+, extending the earlier work of Coulson and Duncanson and of Toh. Several terms not considered previously in the power series expansion of the wave function in elliptic coordinates were found to be very effective in increasing the binding energy. Calculations with a 20-term wave function gave an equilibrium internuclear separation of 1.432 a0 and a fundamental frequency of 3600 cm−1. A 23-term wave function established 1.68 ev as the lower limit for the corrected dissociation energy.
Bond Rupture and Nonrupture in the Beta Decay of Carbon—14 Studied by Double Isotopic Labeling
Authors: Wolfgang Richard L. , Anderson R. Christian , Dodson Richard W.
Published: January 2005

The effect of beta decay of a constituent carbon atom of the ethane molecule has been studied by a technique of double labeling, with C14H3C14H3. The radioactivity of one of the carbon atoms served as a tracer for the entity which results from the decay of the other to nitrogen when the chemical bond is preserved. It was found that in 47% of the cases the molecular entity was not disrupted but survived as methyl amine, C14H3NH2. This result is in good agreement with theoretical expectations.
Yield of the Ferrous Sulfate Radiation Dosimeter: An Improved Cathode-Ray Determination
Authors: Schuler Robert H. , Allen Augustine O.
Published: January 2005

A redetermination of the absolute yield G of ferrous sulfate oxidation by 2-Mev cathode rays has been made with improved accuracy. The corrections for backscattering and charge transfer have been critically re-examined, the correction for absorption of energy in the windows has been determined experimentally and an improved method of determining the energy of the rays is described. The value of G is 15.45±0.11 and is independent of radiation intensity.
Infrared Studies on the Solvent-Solute Interactions
Authors: Yoshino Tsuneo
Published: January 2005

The solvent effects on the infrared absorption bands of trans-1,4-dichlorocyclohexane in the binary solvent cyclohexane-dioxane were measured. The frequency shifts of band centers are nearly proportional to the mixing ratio of the solvent, while the band widths reach the maxima at the intermediate values of the mixing ratio. These changes of solvent effects agree with the results of computations based on the assumption of the binomial distribution of solvent molecules around the solute molecules. The existence of the maximum of band width is well explained as due to an entropy factor, that is, to the various arrangements of solvent molecules encircling the solute molecules.
Vibrational Spectrum of CF3CN
Authors: Edgell Walter F. , Potter Ralph M.
Published: January 2005

The Raman spectrum of liquid CF3CN has been obtained at −100°C. The infrared spectrum of the gas at room temperature has been obtained from 2 to 38μ. The analysis of these data yield the fundamentals, which are used to interpret the overtone and combination bands. A qualitative discussion of the character of the vibrations, which is based upon comparison with other molecules of the CF3X type, is given in terms of orthogonal characteristic vibrations. The results of a normal coordinate analysis are included.
Molar Refraction of Carbon Dioxide and Its Dependence on Density When Stored in Steel Containers
Authors: Coffin Victor H. , Bennett Clarence E.
Published: January 2005

Precise measurements of molar refraction of carbon dioxide as a function of density from zero to 0.06 gram/cc, extend the work previously reported. Repeated runs, involving several hundred observations with the displacement interferometer, indicated an unmistakable but unaccountable negative variation of molar refraction as a function of density, until it was discovered that the age of the gas affected the results. Several hundred additional readings made on samples of gas of various ages, with and without a drying tube of magnesium perchlorate in the line, show that the molar refraction of fresh CO2 is independent of density, as would be expected of a nonpolar substance. It is suggested that as ``bone dry'' CO2 ages under pressure in steel cylinders for periods of a year or more, small amounts of CO are formed by chemical reaction. Supporting evidence for this view has been obtained by measuring the decrease in mass of a carefully weighed sample of CuO in a glass tube, as a measured volume of the CO2 gas was passed through it at a temperature of 250°C. Because CO is strongly polar, traces of it would account for a variation of molar refraction with density such as has been observed in increasing proportions for samples of CO2 ranging in age from one to several years.
Kinetics of the Surface Degradation of Polymethylmethacrylate
Authors: Chaiken R. F. , Andersen W. H. , Barsh M. K. , Mishuck E. , Moe G. , Schultz R. D.
Published: January 2005

The surface degradation of both linear and crosslinked polymethylmethacrylate (PMM) has been studied over the surface temperature range of 550° to 910°K by means of a hot-plate pyrolysis technique. It was demonstrated that surface gasification due to the high heat flux at the decomposing PMM surface involves a depolymerization process and surface desorption of methylmethacrylate monomer. The apparent activation energy for the linear rate of regression of the solid PMM surface (linear pyrolysis rate) was found to decrease with increasing surface temperature, approaching a limiting constant value of 11.2±0.6 kcal/mole at ∼650°K for linear PMM and at ∼770°K for crosslinked PMM. The mechanism for the surface degradation is depicted as (1) formation of monomer in the surface substrate, (2) diffusion of monomer to the surface, and (3) desorption of monomer from the surface. The linear pyrolysis rate data are correlated by means of an absolute rate theory treatment of surface decomposition. The experimental results are in good agreement with the theory.
Mass Spectrum of Propane: Isotope Effect and Metastable Ions
Authors: Kropf Allen , Eyring Edward M. , Wahrhaftig Austin L. , Eyring Henry
Published: January 2005

The mass spectra of propane and of propane-2,2-d2 have been calculated assuming that the mass spectra result from successive and competing unimolecular reactions following initial vertical ionization of the parent molecules. Reasonable agreement with experiment is found for the change in mass spectral pattern with deuterium substitution. The metastable ion peaks are shown to be a normal part of the mass spectrum.
Microwave Spectrum and Molecular Structure of Formamide
Authors: Costain C. C. , Dowling J. M.
Published: January 2005

The microwave spectra of ten isotopic species of formamide (H2N–CHO) have been investigated. Type a and type b transitions have been identified and measured for all ten species. The inertial defect is found to decrease whenever a heavier isotope is substituted for any atom in the NH2 group, and in fact is negative for four of the species studied. It is concluded that the molecule is nonplanar with the H2N–C group forming a shallow pyramid. The structural parameters deduced from the rotational constants are: r(N–H′, where H′ is trans to the aldehyde hydrogen) = 1.014±0.005 A, r(N–H″, where H″ is cis to the aldehyde hydrogen) = 1.002±0.005 A, r(N–C) = 1.376±0.010 A, r(C–H) = 1.102±0.010 A, r(C=O) = 1.193±0.020 A, ∠H′NH″ = 118°53′ ±40′, ∠H″NC = 120°37′±40′, ∠H′NC = 117°9′±40′, ∠NCO = 123°48′±40′, ∠NCH = 113°14′±40′ and ∠OCH = 122°58′±40′. The dihedral angles between the H′NC plane and the NCO plane, and between the H″NC plane and the NCH plane, are 7°±5°, and 12°±5°, respectively.

In all the spectra investigated each line was accompanied by a vibrational satellite line of anomalously high intensity. Measurements of relative intensities were carried out for H2N14–CHO, cis- and trans-HDN14–CHO, and D2N14–CHO. The energy levels (above the zero point) deduced from these measurements show a very large isotope shift, and are interpreted as being due to the first excited state of the NH2 wagging frequency. A pyramidal model for formamide will have two equilibrium configurations separated by a potential barrier. With a Manning type potential, a barrier of 370±50 cm−1, hindering the ``inversion-wagging'' type of motion, is determined. The equilibrium value of the normal coordinate calculated from the Manning potential is found to be in good agreement with that found in the structure determination.
Electronic Structure of CH2 and CH3
Authors: Padgett A. , Krauss M.
Published: January 2005

The self-consistent field molecular orbital method is applied to the calculation of the ground states of the CH2 and CH3 molecules. All electrons are explicitly considered but the three- and four-center electron repulsion integrals were approximated. Results are reported for the dissociation energies, excitation energies, ionization potentials, and the hyperfine splitting constants for the Fermi or ``contact'' term. The values reported for the dissociation energies are in poor agreement with experiment but some qualitative insight into the bonding of these molecules is obtained by an electron population analysis.
Theory of Flame Propagation in Solid Nitrogen at Low Temperatures
Authors: Reed S. G. , Herzfeld C. M.
Published: January 2005

A theory for a flame in a solid whose speed is controlled by diffusion of radicals and heat is applied to slowly propagating flashes observed in solid nitrogen deposited at 4°K from a microwave discharge. Reasonable agreement is obtained with observed speeds.
Bimolecular Reaction Rates in Solids and Liquids
Authors: Waite Thomas R.
Published: January 2005

The purposes of this article are: (1) to call attention to the fact that bimolecular reactions (A+B→AB) in solids and liquids do not, in general, follow simple second-order kinetics and, (2) to discuss some of the complications arising when deviations occur. In a previous paper a general expression for the rate of bimolecular reactions in liquids and solids was derived. The general reaction rate is second-order in the concentrations but the ``rate constant'' is time dependent. That expression is simplified and presented here in terms of three physically significant parameters, D, the sum of the diffusion coefficients of species A and B, r0, the A—B capture radius, and s, the ratio of the probability that a pair of particles A—B separated by a capture radius r0 will react, to the probability that they will diffuse apart before reaction can occur. The dependence of the ``rate constants'' on these parameters and on the time is illustrated graphically. The physical significance of the limiting cases is discussed. A simple, accurate, physically meaningful approximation to the rather abstract general rate expression is presented. An experimental method of distinguishing bimolecular reactions when they do not follow simple second-order kinetics is discussed. Reactions involving particles with long-range forces are considered briefly.
Determination of Atomic Distributions in Liquid Lead-Bismuth Alloys by Neutron and X-Ray Diffraction
Authors: Sharrah Paul C. , Petz John I. , Kruh Robert F.
Published: January 2005

The intensity of scattered neutrons and x-rays has been measured for molten alloys and pure components in the system lead-bismuth. A specially designed diffraction spectrometer has been constructed for the x-ray determinations. The diffraction data have been treated to give atom distributions, and the first main peak in the distribution curves for solutions up to about 60 wt % bismuth corresponds to 12 nearest neighbors, with the value falling to about 7.7 for pure bismuth. No unusual features have been found in the eutectic region, but the density decrease on melting of lead-rich solids is puzzling in view of the retention of 12 nearest neighbors at a mean distance shorter than in the crystal. A model of average pentagonal dodecahedral coordination is suggested to account for this and for the spacing of first maxima in the distribution curves.
Vibration-Rotation Bands of Ammonia. IV. The Stretching Fundamentals and Associated Bands near 3 μ
Authors: Benedict W. S. , Plyler Earle K. , Tidwell E. D.
Published: January 2005

High-resolution spectra of NH3, yielding 1800 lines between 3060–3580 cm−1, are presented. Analysis of the ν3 fundamental is complete through J′=9 and presents no unexpected features. Resolution of the K substructure in the ν1 fundamental shows that several perturbations are present. The most important of these, involving a Fermi resonance with the parallel component of 2ν4, and a Coriolis resonance with its perpendicular component, are clarified. Lines in both components of 2ν4 are identified through J′=6, and a strong Coriolis interaction between the l=0 and l=2 states is observed and discussed.
Molecular Orbital Studies of Diatomic Molecules. I. Method of Computation for Single Configurations of Heteronuclear Systems
Authors: Harris Frank E.
Published: January 2005

This paper describes a method of molecular orbital calculation for heteronuclear diatomic molecules, in the approximation of a single spatial configuration which is a product of one-electron functions. The method is applicable to systems in which the one-electron orbitals are not required to be either orthogonal or filled in pairs. A practical procedure is presented for treating permutational symmetry and spin for an arbitrary spatial wave function, and using this procedure we consider simultaneously all the spin configurations associated with the chosen spatial wave function. The wave functions used are parametric expressions in spheroidal coordinates, and include the usual Slater orbitals as special cases. All necessary integrals are evaluated in a manner suitable for machine computation. A computer program to implement this method of calculation has been prepared, and with it an approximate energy level for a 6-electron molecule can be obtained in about 8 min. Provision was made to program the computer to vary the parameters of the wave functions so as to find automatically the wave function of minimum energy of the parametric form chosen. Only a part of the calculation need be repeated after varying parameters, and the optimum retention of computed data for re-use is discussed.
Isotropic Proton Hyperfine Interaction in the Methyl Radical
Authors: Higuchi Jiro , Aono Shigeyuki
Published: January 2005

The isotropic hyperfine interactions of radicals or ions have been discussed from the viewpoint of the self-consistent field (SCF) molecular orbital theory. In these phenomena, the most important electron configurations concerned are those arising due to the one electron excitations from the double occupied orbital to the vacant orbital together with the lowest energy configuration. The proton hyperfine splitting of the methyl radical was calculated nonempirically by using the SCF-LCAO-MOs in adopting the first order perturbation. The agreement with the observed value is quite good when one uses MOs that include the 3s AO of carbon atom, while it is not so satisfactory in the case of the MOs without the 3s AO, because of the improvement of the form of the totally symmetric antibonding vacant orbital which gives the main contribution to the phenomena.
Theory of Ortho-Para Hydrogen Separation by Adsorption at Low Temperatures, Isotope Separation
Authors: White David , Lassettre Edwin N.
Published: January 2005

A theory of separation of ortho and para hydrogen, by adsorption at low temperatures, is developed by considering the energy levels of a three-dimensional hindered rotator. The Schroedinger equation and boundary conditions are identical with those for prolate spheroidal wave functions and tables of the latter have been employed in calculating the energies as functions of the barrier height. Separation factors, at low surface coverage, have also been computed as a function of barrier height and these pass continuously from unity at zero barrier height over into the limiting separation factor for a two-dimensional rotator (in the adsorbed state) which was used by Sandler in the approximate calculation of separation factors. The theory predicts that ortho hydrogen is more strongly adsorbed than para hydrogen at all barrier heights and that para deuterium is more strongly adsorbed than ortho deuterium. Moreover, the ortho-para hydrogen separation factor is larger at all barrier heights than the para-ortho separation factor for deuterium. These results agree with the experiments of Cunningham, Chapin, and Johnston. Calculated and observed separation factors for hydrogen and deuterium (at low surface coverages) are not in accurate quantitative agreement, however this may be due to the fact that experimental separation factors for both isotopes were not determined under comparable conditions. Calculations have been made first by assuming that rotation and (center of mass) vibration are separable. This model is then refined to take into account the interaction of rotation and vibration.

The separation of the hydrogen-deuterium isotopes is also considered. Although the inclusion of interaction between vibration and rotation does not greatly change the ortho-para separation factors, this effect has a marked influence on the calculated isotope separation factors. It is of considerable interest that isotope separation factors are strongly dependent on the ortho-para composition of the isotope mixture, at least at low surface coverages, in the theory developed here.
Burning Rates of Solid Propellants
Authors: Rosen Gerald
Published: January 2005

The burning mechanism of a solid propellant is described in terms of a pyrolysis law, a premixed laminar flame, and nothing more. A quantitatively accurate burning rate formula is derived from the theory. The predicted burning rate pressure dependence agrees with the experimental results for ammonium perchlorate propellants.
Solution at High Density to the Born-Green Equation
Authors: Broyles A. A.
Published: January 2005

A solution to the Born-Green integral equation with the Lennard-Jones potential at v/v*=n−1a−3=0.9 is presented. Its asymptotic form is found to be 1–38.9r−5 sin (2πr−2.928), and its integral over the volume τ of the system is τ−2.06. The value of E′/RT is found to be −2.6 and of pv/RT is 3.8. The magnitudes of these thermodynamic quantities are compared with those obtained by the Monte Carlo method.